complete day 7

10 files changed, 2664 insertions, 2 deletions

diff --git a/Cargo.lock b/Cargo.lock
index bf29a61..c35e43f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -163,6 +163,24 @@ dependencies = [
 ]
 
 [[package]]
+name = "day07a"
+version = "0.1.0"
+dependencies = [
+ "clap",
+ "itertools",
+ "nom",
+]
+
+[[package]]
+name = "day07b"
+version = "0.1.0"
+dependencies = [
+ "clap",
+ "itertools",
+ "nom",
+]
+
+[[package]]
 name = "either"
 version = "1.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index 44b90b0..9b6bd85 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,8 +13,8 @@ members = [
     "day05b",
     "day06a",
     "day06b",
-    # "day07a",
-    # "day07b",
+    "day07a",
+    "day07b",
     # "day08a",
     # "day08b",
     # "day09a",
diff --git a/day07a/Cargo.toml b/day07a/Cargo.toml
new file mode 100644
index 0000000..94db85a
--- /dev/null
+++ b/day07a/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "day07a"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+clap = { version = "3.2.20", features = ["derive"] }
+nom = "7.1.1"
+itertools = "0.10.5"
diff --git a/day07a/examples/input.txt b/day07a/examples/input.txt
new file mode 100644
index 0000000..1c87c00
--- /dev/null
+++ b/day07a/examples/input.txt
@@ -0,0 +1,979 @@
+$ cd /
+$ ls
+dir plws
+dir pwlbgbz
+dir pwtpltr
+dir szn
+$ cd plws
+$ ls
+dir ffpzc
+dir frcmjzts
+92461 nbvnzg
+dir phqcg
+21621 vqgsglwq
+$ cd ffpzc
+$ ls
+48459 dzdfc.vqq
+143107 jql.jzl
+208330 mmnvqn.hqb
+290122 svjvhflz
+218008 wjlmgq
+$ cd ..
+$ cd frcmjzts
+$ ls
+dir bsltmjz
+dir jfzgrbm
+$ cd bsltmjz
+$ ls
+34237 dzdfc.vqq
+58741 mdgdhqgw
+$ cd ..
+$ cd jfzgrbm
+$ ls
+132811 fcmpng
+103661 lgt.swt
+173031 vqgsglwq
+29134 wprjfg.zbr
+$ cd ..
+$ cd ..
+$ cd phqcg
+$ ls
+955 jgfs.zjw
+$ cd ..
+$ cd ..
+$ cd pwlbgbz
+$ ls
+dir gbg
+dir mjzhcwrd
+dir njcscpj
+dir sphbzn
+dir tbgjpphc
+55938 tvrfpczc.djm
+4840 twd
+$ cd gbg
+$ ls
+287003 fcsjl.bzm
+dir wgq
+$ cd wgq
+$ ls
+22963 fcsjl.fcm
+$ cd ..
+$ cd ..
+$ cd mjzhcwrd
+$ ls
+228632 clfnpmbq.zmb
+28276 dzdfc.vqq
+2982 tdbg.wgn
+$ cd ..
+$ cd njcscpj
+$ ls
+dir dqzgqgv
+275186 ffpzc
+192491 gjnflc.plq
+$ cd dqzgqgv
+$ ls
+70309 dzdfc.vqq
+56139 fcsjl
+142095 sgwz.cdz
+dir snjntth
+dir sphbzn
+284618 wjlmgq
+$ cd snjntth
+$ ls
+51918 ffpzc
+dir vrfgfds
+$ cd vrfgfds
+$ ls
+155233 jlscz
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+dir qbzwrrw
+dir qwpzn
+$ cd qbzwrrw
+$ ls
+278531 fcsjl.tqj
+211591 snjntth.gpd
+$ cd ..
+$ cd qwpzn
+$ ls
+174183 vqgsglwq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+185471 bsltmjz.fqz
+dir bsvh
+dir fvzcs
+dir ndw
+dir nlml
+dir pcbt
+286260 zhcmrpvt
+$ cd bsvh
+$ ls
+130814 wjlmgq
+$ cd ..
+$ cd fvzcs
+$ ls
+dir cgmv
+dir ggzwljr
+298241 qvzghdpw.lms
+dir snjntth
+dir sphbzn
+$ cd cgmv
+$ ls
+46843 dzdfc.vqq
+dir lmqcbbm
+dir rstcqsmd
+215261 snjntth
+$ cd lmqcbbm
+$ ls
+229898 bdmbvgp
+25529 ffpzc.stm
+16871 lnpjzvg.qlj
+$ cd ..
+$ cd rstcqsmd
+$ ls
+289038 zrbbbwng.smf
+$ cd ..
+$ cd ..
+$ cd ggzwljr
+$ ls
+198200 bcthn
+$ cd ..
+$ cd snjntth
+$ ls
+191672 fwp.phf
+68229 hzs.zpg
+dir pggcwb
+222426 qbv.bwj
+dir snjntth
+155354 vmqcm
+$ cd pggcwb
+$ ls
+154272 fqztwvnv.lvv
+dir pdjg
+62393 vqgsglwq
+dir wjhrtg
+$ cd pdjg
+$ ls
+260644 gvhlrcf
+209906 wpls.pbd
+$ cd ..
+$ cd wjhrtg
+$ ls
+148640 dljf.zrq
+172168 dzdfc.vqq
+196203 hjdphcfm
+247620 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+37467 ndlshlmj.cjq
+257404 snjntth.nsf
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+64082 bfdv.lwv
+dir bsltmjz
+58942 dzdfc.vqq
+dir snjntth
+$ cd bsltmjz
+$ ls
+dir bsqqdr
+266007 fcsjl.gfm
+dir ffpzc
+dir frsmrd
+72122 nthnhzwf
+286705 wjlmgq
+$ cd bsqqdr
+$ ls
+117496 wcqt
+$ cd ..
+$ cd ffpzc
+$ ls
+280224 mmnvqn.hqb
+105346 vrr
+$ cd ..
+$ cd frsmrd
+$ ls
+111509 sphbzn.shz
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+177491 mplj
+9029 pvbz.jwn
+92891 snjntth.zrv
+203356 vnnnw.gql
+134728 vqgsglwq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ndw
+$ ls
+241303 bht.rpj
+173068 vqgsglwq
+$ cd ..
+$ cd nlml
+$ ls
+228982 hzglfpvq.ftt
+114981 sgwz.cdz
+$ cd ..
+$ cd pcbt
+$ ls
+dir bsltmjz
+dir ffpzc
+dir fjsjwfg
+dir fwm
+dir jvwt
+227943 tmr.jdc
+dir vwpqzdwh
+31258 wjlmgq
+$ cd bsltmjz
+$ ls
+177750 bsltmjz.spj
+dir ffpzc
+dir flrpwfs
+138824 mtmdtcpv.cfj
+165770 wzqwczj.qwn
+$ cd ffpzc
+$ ls
+179645 snjntth.dss
+$ cd ..
+$ cd flrpwfs
+$ ls
+60566 wvjq.gmm
+$ cd ..
+$ cd ..
+$ cd ffpzc
+$ ls
+97847 qzhhtmd.bhw
+1197 vqgsglwq
+$ cd ..
+$ cd fjsjwfg
+$ ls
+152232 dnsdd.jgz
+181301 gsb.wsh
+dir jqpb
+dir jscbg
+dir snjntth
+227677 snjntth.vvg
+dir sphbzn
+75358 vqgsglwq
+2589 wjlmgq
+$ cd jqpb
+$ ls
+253403 mmnvqn.hqb
+108325 rvq.mrc
+$ cd ..
+$ cd jscbg
+$ ls
+dir dtm
+dir gsdnz
+208269 prh
+25977 qdzljgh
+169262 vmnq.mth
+$ cd dtm
+$ ls
+80072 gzqnb
+$ cd ..
+$ cd gsdnz
+$ ls
+dir dsqzjs
+297895 sgwz.cdz
+129983 vqgsglwq
+$ cd dsqzjs
+$ ls
+2621 jqrlsf.gzs
+164844 snjntth
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+118553 cbhql
+dir ffpzc
+dir snjntth
+$ cd ffpzc
+$ ls
+dir lmn
+12104 tvlwn.vhh
+$ cd lmn
+$ ls
+46401 bsltmjz
+96888 shrnqhvq
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+dir snjntth
+dir vlnfhbq
+dir wpwl
+$ cd snjntth
+$ ls
+dir ctj
+$ cd ctj
+$ ls
+82485 fcsjl.lfl
+$ cd ..
+$ cd ..
+$ cd vlnfhbq
+$ ls
+250106 qvf
+$ cd ..
+$ cd wpwl
+$ ls
+153950 cmsd.rlg
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+dir glgq
+$ cd glgq
+$ ls
+285182 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fwm
+$ ls
+251865 ffpzc.qgb
+279522 zvvpfqtp
+$ cd ..
+$ cd jvwt
+$ ls
+48990 bsltmjz.nzp
+219604 ffpzc
+69573 mvmdfzr.lwb
+$ cd ..
+$ cd vwpqzdwh
+$ ls
+267581 pvcch
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd tbgjpphc
+$ ls
+255571 dstpcgr.tfq
+dir fdbwbrpp
+dir gjzwh
+dir hjvrtjt
+dir rhzczj
+292888 sgwz.cdz
+dir wlzhr
+149395 wnfzrqgz.dtn
+$ cd fdbwbrpp
+$ ls
+dir ffpzc
+dir qbrth
+51164 qprp
+dir slpt
+117026 sphbzn
+295685 vqgsglwq
+dir znmj
+$ cd ffpzc
+$ ls
+dir jhnzrdvb
+$ cd jhnzrdvb
+$ ls
+217775 ffpzc.sgw
+$ cd ..
+$ cd ..
+$ cd qbrth
+$ ls
+183969 lpbwgfjv.vcg
+47333 wjlmgq
+$ cd ..
+$ cd slpt
+$ ls
+32343 tqhtj.jwz
+$ cd ..
+$ cd znmj
+$ ls
+55058 mmnvqn.hqb
+$ cd ..
+$ cd ..
+$ cd gjzwh
+$ ls
+dir dvcbcd
+202530 dzdfc.vqq
+dir fsgz
+dir hfrrqq
+54897 jlzn.qsn
+16097 ldzqsbb.jzl
+225078 pswccrd
+dir rqqmldw
+292464 rzrdhbp.vld
+dir ssqbqqp
+dir zsztqrc
+$ cd dvcbcd
+$ ls
+187837 dzdfc.vqq
+dir jlwtvf
+dir jnjvshs
+164053 nrf.fqd
+5665 tlp.jmt
+13801 wjlmgq
+$ cd jlwtvf
+$ ls
+219985 sphbzn.dvj
+$ cd ..
+$ cd jnjvshs
+$ ls
+dir bsltmjz
+dir nrpm
+$ cd bsltmjz
+$ ls
+152972 qgdqj
+$ cd ..
+$ cd nrpm
+$ ls
+18509 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fsgz
+$ ls
+224576 mmnvqn.hqb
+$ cd ..
+$ cd hfrrqq
+$ ls
+dir bwgsnfvb
+dir fcsjl
+294608 ffpzc.gvm
+136880 qjcgtw
+dir sphbzn
+$ cd bwgsnfvb
+$ ls
+29735 dzdfc.vqq
+dir wstmzfml
+$ cd wstmzfml
+$ ls
+158447 bnvhbvvc.nrt
+59889 jclclgd
+$ cd ..
+$ cd ..
+$ cd fcsjl
+$ ls
+138297 ffpzc.szw
+$ cd ..
+$ cd sphbzn
+$ ls
+dir wqdths
+$ cd wqdths
+$ ls
+8326 cgvtw.jpz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd rqqmldw
+$ ls
+226757 dzdfc.vqq
+115055 mwb.btc
+dir qpts
+298524 sgwz.cdz
+$ cd qpts
+$ ls
+60860 bsltmjz.frp
+dir fcsjl
+94904 sgwz.cdz
+dir wnmqqspz
+$ cd fcsjl
+$ ls
+25082 mmnvqn.hqb
+$ cd ..
+$ cd wnmqqspz
+$ ls
+165529 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ssqbqqp
+$ ls
+192477 pvrgm
+$ cd ..
+$ cd zsztqrc
+$ ls
+254053 lht.htn
+$ cd ..
+$ cd ..
+$ cd hjvrtjt
+$ ls
+189942 fwps
+$ cd ..
+$ cd rhzczj
+$ ls
+36502 bmtfr
+dir ffjz
+35148 nctfhmzm.vsz
+dir qdgjzcz
+208196 rwql
+79863 sgwz.cdz
+dir snjntth
+$ cd ffjz
+$ ls
+dir grsvhwm
+$ cd grsvhwm
+$ ls
+50231 fwj.rdv
+dir snjntth
+$ cd snjntth
+$ ls
+dir dtbgb
+$ cd dtbgb
+$ ls
+150245 vdflm.lmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qdgjzcz
+$ ls
+222389 dzdfc.vqq
+$ cd ..
+$ cd snjntth
+$ ls
+56794 mmnvqn.hqb
+$ cd ..
+$ cd ..
+$ cd wlzhr
+$ ls
+116628 bsltmjz
+60122 jqpbsgnr.fgb
+252605 lfss
+300065 qwjdl.vhr
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd pwtpltr
+$ ls
+dir dplsvrhl
+140951 gwtfzqvd.znb
+dir jbvdb
+dir jst
+dir qhjv
+dir snjntth
+$ cd dplsvrhl
+$ ls
+272101 fcsjl
+dir ffpzc
+58852 mmnvqn.hqb
+dir mnhntjz
+91899 sgwz.cdz
+228077 snjntth.btv
+$ cd ffpzc
+$ ls
+5499 bsltmjz
+dir qmfwpjhl
+dir rsrb
+dir wgt
+$ cd qmfwpjhl
+$ ls
+300362 dzdfc.vqq
+$ cd ..
+$ cd rsrb
+$ ls
+252983 dzdfc.vqq
+107744 ltssrgqb.zvj
+214895 rhglgcwr.wpw
+249727 sgwz.cdz
+$ cd ..
+$ cd wgt
+$ ls
+141984 dzdfc.vqq
+194686 mmnvqn.hqb
+258023 pgr
+$ cd ..
+$ cd ..
+$ cd mnhntjz
+$ ls
+dir bdvght
+dir jprwchh
+dir snjntth
+$ cd bdvght
+$ ls
+243166 vpsvjdq.wsn
+$ cd ..
+$ cd jprwchh
+$ ls
+178943 bmpc.bjb
+$ cd ..
+$ cd snjntth
+$ ls
+dir nlbm
+dir zjmjntff
+$ cd nlbm
+$ ls
+33050 fcsjl.rcc
+dir sphbzn
+17446 wjlmgq
+$ cd sphbzn
+$ ls
+214563 prrfhff.pbp
+$ cd ..
+$ cd ..
+$ cd zjmjntff
+$ ls
+82134 sgwz.cdz
+52203 vrtlgdq.crp
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd jbvdb
+$ ls
+dir wmtjh
+$ cd wmtjh
+$ ls
+dir ggvwn
+$ cd ggvwn
+$ ls
+192285 spqvmf.sdh
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd jst
+$ ls
+dir bsltmjz
+212740 dzdfc.vqq
+dir gncztvtb
+dir jsqjcqnt
+286257 jvs
+36654 sdcsm.mbg
+192040 sgwz.cdz
+dir tbqphzb
+dir vdcqgts
+285843 wjlmgq
+$ cd bsltmjz
+$ ls
+215705 snjntth.gpv
+213665 wjlmgq
+$ cd ..
+$ cd gncztvtb
+$ ls
+229298 vqgsglwq
+$ cd ..
+$ cd jsqjcqnt
+$ ls
+dir bsltmjz
+dir fcsjl
+dir ffpzc
+dir sphbzn
+70864 vqgsglwq
+$ cd bsltmjz
+$ ls
+14981 pqzffzjc
+$ cd ..
+$ cd fcsjl
+$ ls
+140328 jwhczwbc
+$ cd ..
+$ cd ffpzc
+$ ls
+213650 mmnvqn.hqb
+$ cd ..
+$ cd sphbzn
+$ ls
+dir psmtphhq
+dir sphbzn
+$ cd psmtphhq
+$ ls
+dir ffpzc
+123131 tzgwd
+$ cd ffpzc
+$ ls
+49737 cfngvmd
+dir gcnrp
+172799 gmd.cwl
+dir llnztjf
+dir nbqs
+79661 rrqz
+$ cd gcnrp
+$ ls
+283 vqnrgl.vwp
+$ cd ..
+$ cd llnztjf
+$ ls
+63263 tjhm.bwh
+$ cd ..
+$ cd nbqs
+$ ls
+dir vssmq
+$ cd vssmq
+$ ls
+88980 dzdfc.vqq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+20140 fcsjl.zrs
+260579 snjntth
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd tbqphzb
+$ ls
+93470 sgwz.cdz
+$ cd ..
+$ cd vdcqgts
+$ ls
+223564 dzdfc.vqq
+dir ffpzc
+dir gwhfgwf
+dir nbjtqnng
+dir snjntth
+$ cd ffpzc
+$ ls
+42813 qwwmw.nmt
+$ cd ..
+$ cd gwhfgwf
+$ ls
+59918 jvfv.mpm
+dir mjl
+211039 pcwl
+$ cd mjl
+$ ls
+13004 pgjb.tpq
+195995 tms.fjz
+$ cd ..
+$ cd ..
+$ cd nbjtqnng
+$ ls
+107058 dzdfc.vqq
+dir ldrsd
+111631 vqgsglwq
+104599 wbzmdljw.tjq
+155747 wjlmgq
+$ cd ldrsd
+$ ls
+107439 jvjm
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+242680 fgrt.gng
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qhjv
+$ ls
+dir bmnm
+68453 hjjpdgn.hwl
+dir sjlbj
+dir vqnrj
+$ cd bmnm
+$ ls
+1238 vqgsglwq
+$ cd ..
+$ cd sjlbj
+$ ls
+44239 wzzbtmrz.gml
+$ cd ..
+$ cd vqnrj
+$ ls
+3286 bsltmjz.qlc
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+130833 blm.wmt
+dir snjntth
+dir tcnmbcgg
+218869 wjlmgq
+$ cd snjntth
+$ ls
+dir snmrdfbt
+$ cd snmrdfbt
+$ ls
+281025 bzrsds.lfg
+$ cd ..
+$ cd ..
+$ cd tcnmbcgg
+$ ls
+194998 fcsjl
+dir qdrmpqgn
+dir rzqd
+dir tcsds
+$ cd qdrmpqgn
+$ ls
+165713 qmzgt.tnc
+$ cd ..
+$ cd rzqd
+$ ls
+dir cwhnmlv
+57819 fcsjl
+246864 pjnzdvd.gjm
+$ cd cwhnmlv
+$ ls
+287539 mmnvqn.hqb
+215636 pbnjt.zbn
+124638 sqd
+$ cd ..
+$ cd ..
+$ cd tcsds
+$ ls
+78812 gfmgb.wqj
+218987 hnhfvz.dln
+209640 mzzhqlq.zqp
+102492 nml.ppg
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd szn
+$ ls
+dir fcsjl
+dir snjntth
+dir zjbp
+$ cd fcsjl
+$ ls
+158019 jsv.pmz
+$ cd ..
+$ cd snjntth
+$ ls
+229510 dfvpvp
+191061 fgplbptq.jlt
+dir lfb
+234911 lfsrwr.wcb
+dir lrfcgzl
+48031 stbbw
+219691 vqgsglwq
+dir zshh
+$ cd lfb
+$ ls
+dir btj
+99591 dhrjbvvg.gwm
+137224 dzdfc.vqq
+201972 jtzmqsvj.wnd
+9704 mmnvqn.hqb
+dir pwg
+200308 snjntth.css
+dir wcmhcfm
+dir zwhvmln
+$ cd btj
+$ ls
+dir rnbzdfgn
+51799 wdhsm
+dir wvf
+$ cd rnbzdfgn
+$ ls
+117095 bsltmjz.tlv
+$ cd ..
+$ cd wvf
+$ ls
+dir ffpzc
+dir ncbmgpsc
+dir wtwrmjnt
+$ cd ffpzc
+$ ls
+249919 lsth.fmf
+$ cd ..
+$ cd ncbmgpsc
+$ ls
+147899 dzdfc.vqq
+$ cd ..
+$ cd wtwrmjnt
+$ ls
+252366 pvpdv.jwz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd pwg
+$ ls
+280845 fcsjl.fjz
+44300 sgwz.cdz
+dir snjntth
+229605 vqgsglwq
+$ cd snjntth
+$ ls
+2053 pflvsnzs
+143522 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd wcmhcfm
+$ ls
+229329 qsznhwlw.vjg
+$ cd ..
+$ cd zwhvmln
+$ ls
+dir ffpzc
+dir tjjzbf
+dir wzcq
+$ cd ffpzc
+$ ls
+dir ncnj
+37497 vqgsglwq
+$ cd ncnj
+$ ls
+40920 htbjhjq
+$ cd ..
+$ cd ..
+$ cd tjjzbf
+$ ls
+47522 mczn.spd
+$ cd ..
+$ cd wzcq
+$ ls
+56662 ffpzc.vwp
+dir snjntth
+$ cd snjntth
+$ ls
+117276 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd lrfcgzl
+$ ls
+267485 rsjmpph.qqz
+$ cd ..
+$ cd zshh
+$ ls
+dir ffpzc
+dir gmn
+dir snjntth
+150048 tgtlh
+32020 thfr
+72152 vqgsglwq
+$ cd ffpzc
+$ ls
+dir snjntth
+$ cd snjntth
+$ ls
+224945 dpfpz
+$ cd ..
+$ cd ..
+$ cd gmn
+$ ls
+238996 sgwz.cdz
+$ cd ..
+$ cd snjntth
+$ ls
+86775 dzdfc.vqq
+19560 vshcmjj
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd zjbp
+$ ls
+dir fcsjl
+41522 nlvpb.fpf
+dir nmtjtd
+$ cd fcsjl
+$ ls
+276802 fcsjl.psm
+197934 sgwz.cdz
+$ cd ..
+$ cd nmtjtd
+$ ls
+47477 dvqmqlgw.ths
+51081 vqgsglwq
diff --git a/day07a/examples/test.txt b/day07a/examples/test.txt
new file mode 100644
index 0000000..09a921e
--- /dev/null
+++ b/day07a/examples/test.txt
@@ -0,0 +1,23 @@
+$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k
diff --git a/day07a/src/main.rs b/day07a/src/main.rs
new file mode 100644
index 0000000..bfbbcd3
--- /dev/null
+++ b/day07a/src/main.rs
@@ -0,0 +1,350 @@
+/// --- Day 7: No Space Left On Device ---
+///
+/// You can hear birds chirping and raindrops hitting leaves as the expedition proceeds.
+/// Occasionally, you can even hear much louder sounds in the distance; how big do the
+/// animals get out here, anyway?
+///
+/// The device the Elves gave you has problems with more than just its communication system.  You
+/// try to run a system update:
+///
+/// ```
+/// $ system-update --please --pretty-please-with-sugar-on-top
+/// Error: No space left on device
+/// ```
+///
+/// Perhaps you can delete some files to make space for the update?
+///
+/// You browse around the filesystem to assess the situation and save the resulting terminal output
+/// (your puzzle input).  For example:
+///
+/// ```
+/// $ cd /
+/// $ ls
+/// dir a
+/// 14848514 b.txt
+/// 8504156 c.dat
+/// dir d
+/// $ cd a
+/// $ ls
+/// dir e
+/// 29116 f
+/// 2557 g
+/// 62596 h.lst
+/// $ cd e
+/// $ ls
+/// 584 i
+/// $ cd ..
+/// $ cd ..
+/// $ cd d
+/// $ ls
+/// 4060174 j
+/// 8033020 d.log
+/// 5626152 d.ext
+/// 7214296 k
+/// ```
+///
+/// The filesystem consists of a tree of files (plain data) and directories (which can contain
+/// other directories or files).  The outermost directory is called /.  You can navigate around the
+/// filesystem, moving into or out of directories and listing the contents of the directory you're
+/// currently in.
+///
+/// Within the terminal output, lines that begin with $ are commands you executed, very much like
+/// some modern computers:
+///
+///     cd means change directory. This changes which directory is the current directory, but the
+///     specific result depends on the argument:
+///         cd x moves in one level: it looks in the current directory for the directory named x
+///         and makes it the current directory.
+///         cd .. moves out one level: it finds the directory that contains the current directory,
+///         then makes that directory the current directory.
+///         cd / switches the current directory to the outermost directory, /.
+///     ls means list. It prints out all of the files and directories immediately contained by the
+///     current directory:
+///         123 abc means that the current directory contains a file named abc with size 123.
+///         dir xyz means that the current directory contains a directory named xyz.
+///
+/// Given the commands and output in the example above, you can determine that the filesystem looks
+/// visually like this:
+///
+/// ```
+/// - / (dir)
+///   - a (dir)
+///     - e (dir)
+///       - i (file, size=584)
+///     - f (file, size=29116)
+///     - g (file, size=2557)
+///     - h.lst (file, size=62596)
+///   - b.txt (file, size=14848514)
+///   - c.dat (file, size=8504156)
+///   - d (dir)
+///     - j (file, size=4060174)
+///     - d.log (file, size=8033020)
+///     - d.ext (file, size=5626152)
+///     - k (file, size=7214296)
+/// ```
+///
+/// Here, there are four directories: / (the outermost directory), a and d (which are in /), and e
+/// (which is in a).  These directories also contain files of various sizes.
+///
+/// Since the disk is full, your first step should probably be to find directories that are good
+/// candidates for deletion.  To do this, you need to determine the total size of each directory.
+/// The total size of a directory is the sum of the sizes of the files it contains, directly or
+/// indirectly.  (Directories themselves do not count as having any intrinsic size.)
+///
+/// The total sizes of the directories above can be found as follows:
+///
+///     The total size of directory e is 584 because it contains a single file i of size 584 and no
+///     other directories.
+///     The directory a has total size 94853 because it contains files f (size 29116), g (size
+///     2557), and h.lst (size 62596), plus file i indirectly (a contains e which contains i).
+///     Directory d has total size 24933642.
+///     As the outermost directory, / contains every file.  Its total size is 48381165, the sum of
+///     the size of every file.
+///
+/// To begin, find all of the directories with a total size of at most 100000, then calculate the
+/// sum of their total sizes.  In the example above, these directories are a and e; the sum of
+/// their total sizes is 95437 (94853 + 584). (As in this example, this process can count files
+/// more than once!)
+///
+/// Find all of the directories with a total size of at most 100000. What is the sum of the total
+/// sizes of those directories?
+use clap::Parser;
+use nom::branch::alt;
+use nom::bytes::streaming::tag;
+use nom::character::streaming::{char, newline, not_line_ending, space1, u64};
+use nom::combinator::{map, peek};
+use nom::error::{context, ContextError, ErrorKind as NomErrorKind, ParseError};
+use nom::multi::many_till;
+use nom::sequence::{delimited, preceded, terminated, tuple};
+use nom::IResult;
+
+use std::collections::HashMap;
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::BufReader;
+use std::iter::*;
+use std::path::PathBuf;
+
+pub type Input<'a> = &'a str;
+pub type Result<'a, T> = IResult<Input<'a>, T, Error<Input<'a>>>;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ErrorKind {
+    Nom(NomErrorKind),
+    Context(&'static str),
+    Custom(String),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Error<I> {
+    pub errors: Vec<(I, ErrorKind)>,
+}
+
+impl<I> ParseError<I> for Error<I> {
+    fn from_error_kind(input: I, kind: NomErrorKind) -> Self {
+        let errors = vec![(input, ErrorKind::Nom(kind))];
+        Self { errors }
+    }
+
+    fn append(input: I, kind: NomErrorKind, mut other: Self) -> Self {
+        other.errors.push((input, ErrorKind::Nom(kind)));
+        other
+    }
+}
+
+impl<I> ContextError<I> for Error<I> {
+    fn add_context(input: I, ctx: &'static str, mut other: Self) -> Self {
+        other.errors.push((input, ErrorKind::Context(ctx)));
+        other
+    }
+}
+
+const FILEPATH: &'static str = "examples/input.txt";
+const EOF_CHAR: char = '\0';
+const DIRMAXSIZE: u64 = 100000;
+
+#[derive(Parser, Debug)]
+#[clap(author, version, about, long_about = None)]
+struct Cli {
+    #[clap(short, long, default_value = FILEPATH)]
+    file: PathBuf,
+}
+
+#[derive(Clone, Debug)]
+enum Commands {
+    ChangeDir(String),
+    List(Vec<ListEntry>),
+}
+
+#[derive(Clone, Debug)]
+enum ListEntry {
+    File(FileEntry),
+    Folder(String),
+}
+
+#[derive(Clone, Debug)]
+struct FileEntry {
+    name: String,
+    size: u64,
+}
+
+#[derive(Clone, Debug)]
+struct Arena(Vec<Node>);
+
+#[derive(Clone, Debug)]
+struct Node {
+    size: u64,
+    parent: Option<usize>,
+    children: HashMap<String, usize>,
+}
+
+impl Node {
+    fn new() -> Self {
+        Node {
+            size: 0,
+            parent: None,
+            children: HashMap::new(),
+        }
+    }
+
+    fn with_parent(idx: usize) -> Self {
+        Node {
+            size: 0,
+            parent: Some(idx),
+            children: HashMap::new(),
+        }
+    }
+}
+
+impl Arena {
+    // NOTE: only call this once per node
+    fn consume(&mut self, idx: usize, ls: Vec<ListEntry>) {
+        for le in ls.into_iter() {
+            match le {
+                ListEntry::File(f) => {
+                    let mut iteridx = idx;
+                    loop {
+                        self.0[iteridx].size += f.size;
+                        iteridx = if let Some(pidx) = self.0[iteridx].parent {
+                            pidx
+                        } else {
+                            break;
+                        };
+                    }
+                }
+                ListEntry::Folder(f) => {
+                    let fidx = self.0.len();
+                    self.0.push(Node::with_parent(idx));
+                    self.0[idx].children.insert(f, fidx);
+                }
+            }
+        }
+    }
+
+    fn get(&mut self, idx: usize) -> &mut Node {
+        &mut self.0[idx]
+    }
+}
+
+fn parse_cd(input: &str) -> Result<Commands> {
+    context(
+        "parse_cd",
+        map(
+            delimited(tuple((tag("cd"), space1)), not_line_ending, newline),
+            |s: &str| Commands::ChangeDir(s.to_string()),
+        ),
+    )(input)
+}
+
+fn end_of_file_or_ls(input: &str) -> Result<char> {
+    alt((char(EOF_CHAR), peek(char('$'))))(input)
+}
+
+fn parse_ls(input: &str) -> Result<Commands> {
+    let (input, _) = context("parse_ls", terminated(tag("ls"), newline))(input)?;
+    let (input, (lsv, _)) = many_till(parse_ls_entry, end_of_file_or_ls)(input)?;
+    Ok((input, Commands::List(lsv)))
+}
+
+fn parse_ls_entry(input: &str) -> Result<ListEntry> {
+    context("parse_ls_entry", alt((parse_file, parse_folder)))(input)
+}
+
+fn parse_file(input: &str) -> Result<ListEntry> {
+    map(
+        terminated(tuple((u64, preceded(tag(" "), not_line_ending))), newline),
+        |(size, name): (u64, &str)| {
+            ListEntry::File(FileEntry {
+                name: name.to_string(),
+                size,
+            })
+        },
+    )(input)
+}
+
+fn parse_folder(input: &str) -> Result<ListEntry> {
+    map(
+        delimited(tag("dir "), not_line_ending, newline),
+        |s: &str| ListEntry::Folder(s.to_string()),
+    )(input)
+}
+
+fn parse_cmd(input: &str) -> Result<Commands> {
+    context(
+        "parse_cmd",
+        preceded(tuple((tag("$"), space1)), alt((parse_cd, parse_ls))),
+    )(input)
+}
+
+fn main() {
+    let args = Cli::parse();
+
+    let file = File::open(&args.file).unwrap();
+    let mut reader = BufReader::new(file);
+
+    let mut buf = String::new();
+    let mut cmds = Vec::new();
+    'block: loop {
+        let len = reader.read_line(&mut buf).unwrap();
+        if len == 0 {
+            buf.push(EOF_CHAR);
+        }
+        loop {
+            match parse_cmd(buf.as_str()) {
+                Ok((input, cmd)) => {
+                    cmds.push(cmd);
+                    if len == 0 && input.len() == 0 {
+                        break 'block;
+                    }
+                    let _ = buf.drain(..(buf.len() - input.len()));
+                }
+                Err(err) => match err {
+                    nom::Err::Incomplete(_) => continue 'block,
+                    e @ _ => panic!("buf={} err={}", buf, e),
+                },
+            }
+        }
+    }
+
+    let mut loc = 0;
+    let mut arena = Arena(Vec::new());
+    arena.0.push(Node::new());
+    for cmd in cmds.into_iter() {
+        match cmd {
+            Commands::ChangeDir(dir) => match dir.as_str() {
+                "/" => loc = 0,
+                ".." => loc = arena.get(loc).parent.unwrap(),
+                _ => loc = arena.get(loc).children[&dir],
+            },
+            Commands::List(lsv) => arena.consume(loc, lsv),
+        }
+    }
+
+    let res: u64 = arena
+        .0
+        .into_iter()
+        .filter(|n| n.size <= DIRMAXSIZE)
+        .map(|n| n.size)
+        .sum();
+    println!("{res:?}");
+}
diff --git a/day07b/Cargo.toml b/day07b/Cargo.toml
new file mode 100644
index 0000000..6dc7ca6
--- /dev/null
+++ b/day07b/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "day07b"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+clap = { version = "3.2.20", features = ["derive"] }
+nom = "7.1.1"
+itertools = "0.10.5"
diff --git a/day07b/examples/input.txt b/day07b/examples/input.txt
new file mode 100644
index 0000000..1c87c00
--- /dev/null
+++ b/day07b/examples/input.txt
@@ -0,0 +1,979 @@
+$ cd /
+$ ls
+dir plws
+dir pwlbgbz
+dir pwtpltr
+dir szn
+$ cd plws
+$ ls
+dir ffpzc
+dir frcmjzts
+92461 nbvnzg
+dir phqcg
+21621 vqgsglwq
+$ cd ffpzc
+$ ls
+48459 dzdfc.vqq
+143107 jql.jzl
+208330 mmnvqn.hqb
+290122 svjvhflz
+218008 wjlmgq
+$ cd ..
+$ cd frcmjzts
+$ ls
+dir bsltmjz
+dir jfzgrbm
+$ cd bsltmjz
+$ ls
+34237 dzdfc.vqq
+58741 mdgdhqgw
+$ cd ..
+$ cd jfzgrbm
+$ ls
+132811 fcmpng
+103661 lgt.swt
+173031 vqgsglwq
+29134 wprjfg.zbr
+$ cd ..
+$ cd ..
+$ cd phqcg
+$ ls
+955 jgfs.zjw
+$ cd ..
+$ cd ..
+$ cd pwlbgbz
+$ ls
+dir gbg
+dir mjzhcwrd
+dir njcscpj
+dir sphbzn
+dir tbgjpphc
+55938 tvrfpczc.djm
+4840 twd
+$ cd gbg
+$ ls
+287003 fcsjl.bzm
+dir wgq
+$ cd wgq
+$ ls
+22963 fcsjl.fcm
+$ cd ..
+$ cd ..
+$ cd mjzhcwrd
+$ ls
+228632 clfnpmbq.zmb
+28276 dzdfc.vqq
+2982 tdbg.wgn
+$ cd ..
+$ cd njcscpj
+$ ls
+dir dqzgqgv
+275186 ffpzc
+192491 gjnflc.plq
+$ cd dqzgqgv
+$ ls
+70309 dzdfc.vqq
+56139 fcsjl
+142095 sgwz.cdz
+dir snjntth
+dir sphbzn
+284618 wjlmgq
+$ cd snjntth
+$ ls
+51918 ffpzc
+dir vrfgfds
+$ cd vrfgfds
+$ ls
+155233 jlscz
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+dir qbzwrrw
+dir qwpzn
+$ cd qbzwrrw
+$ ls
+278531 fcsjl.tqj
+211591 snjntth.gpd
+$ cd ..
+$ cd qwpzn
+$ ls
+174183 vqgsglwq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+185471 bsltmjz.fqz
+dir bsvh
+dir fvzcs
+dir ndw
+dir nlml
+dir pcbt
+286260 zhcmrpvt
+$ cd bsvh
+$ ls
+130814 wjlmgq
+$ cd ..
+$ cd fvzcs
+$ ls
+dir cgmv
+dir ggzwljr
+298241 qvzghdpw.lms
+dir snjntth
+dir sphbzn
+$ cd cgmv
+$ ls
+46843 dzdfc.vqq
+dir lmqcbbm
+dir rstcqsmd
+215261 snjntth
+$ cd lmqcbbm
+$ ls
+229898 bdmbvgp
+25529 ffpzc.stm
+16871 lnpjzvg.qlj
+$ cd ..
+$ cd rstcqsmd
+$ ls
+289038 zrbbbwng.smf
+$ cd ..
+$ cd ..
+$ cd ggzwljr
+$ ls
+198200 bcthn
+$ cd ..
+$ cd snjntth
+$ ls
+191672 fwp.phf
+68229 hzs.zpg
+dir pggcwb
+222426 qbv.bwj
+dir snjntth
+155354 vmqcm
+$ cd pggcwb
+$ ls
+154272 fqztwvnv.lvv
+dir pdjg
+62393 vqgsglwq
+dir wjhrtg
+$ cd pdjg
+$ ls
+260644 gvhlrcf
+209906 wpls.pbd
+$ cd ..
+$ cd wjhrtg
+$ ls
+148640 dljf.zrq
+172168 dzdfc.vqq
+196203 hjdphcfm
+247620 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+37467 ndlshlmj.cjq
+257404 snjntth.nsf
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+64082 bfdv.lwv
+dir bsltmjz
+58942 dzdfc.vqq
+dir snjntth
+$ cd bsltmjz
+$ ls
+dir bsqqdr
+266007 fcsjl.gfm
+dir ffpzc
+dir frsmrd
+72122 nthnhzwf
+286705 wjlmgq
+$ cd bsqqdr
+$ ls
+117496 wcqt
+$ cd ..
+$ cd ffpzc
+$ ls
+280224 mmnvqn.hqb
+105346 vrr
+$ cd ..
+$ cd frsmrd
+$ ls
+111509 sphbzn.shz
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+177491 mplj
+9029 pvbz.jwn
+92891 snjntth.zrv
+203356 vnnnw.gql
+134728 vqgsglwq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ndw
+$ ls
+241303 bht.rpj
+173068 vqgsglwq
+$ cd ..
+$ cd nlml
+$ ls
+228982 hzglfpvq.ftt
+114981 sgwz.cdz
+$ cd ..
+$ cd pcbt
+$ ls
+dir bsltmjz
+dir ffpzc
+dir fjsjwfg
+dir fwm
+dir jvwt
+227943 tmr.jdc
+dir vwpqzdwh
+31258 wjlmgq
+$ cd bsltmjz
+$ ls
+177750 bsltmjz.spj
+dir ffpzc
+dir flrpwfs
+138824 mtmdtcpv.cfj
+165770 wzqwczj.qwn
+$ cd ffpzc
+$ ls
+179645 snjntth.dss
+$ cd ..
+$ cd flrpwfs
+$ ls
+60566 wvjq.gmm
+$ cd ..
+$ cd ..
+$ cd ffpzc
+$ ls
+97847 qzhhtmd.bhw
+1197 vqgsglwq
+$ cd ..
+$ cd fjsjwfg
+$ ls
+152232 dnsdd.jgz
+181301 gsb.wsh
+dir jqpb
+dir jscbg
+dir snjntth
+227677 snjntth.vvg
+dir sphbzn
+75358 vqgsglwq
+2589 wjlmgq
+$ cd jqpb
+$ ls
+253403 mmnvqn.hqb
+108325 rvq.mrc
+$ cd ..
+$ cd jscbg
+$ ls
+dir dtm
+dir gsdnz
+208269 prh
+25977 qdzljgh
+169262 vmnq.mth
+$ cd dtm
+$ ls
+80072 gzqnb
+$ cd ..
+$ cd gsdnz
+$ ls
+dir dsqzjs
+297895 sgwz.cdz
+129983 vqgsglwq
+$ cd dsqzjs
+$ ls
+2621 jqrlsf.gzs
+164844 snjntth
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+118553 cbhql
+dir ffpzc
+dir snjntth
+$ cd ffpzc
+$ ls
+dir lmn
+12104 tvlwn.vhh
+$ cd lmn
+$ ls
+46401 bsltmjz
+96888 shrnqhvq
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+dir snjntth
+dir vlnfhbq
+dir wpwl
+$ cd snjntth
+$ ls
+dir ctj
+$ cd ctj
+$ ls
+82485 fcsjl.lfl
+$ cd ..
+$ cd ..
+$ cd vlnfhbq
+$ ls
+250106 qvf
+$ cd ..
+$ cd wpwl
+$ ls
+153950 cmsd.rlg
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+dir glgq
+$ cd glgq
+$ ls
+285182 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fwm
+$ ls
+251865 ffpzc.qgb
+279522 zvvpfqtp
+$ cd ..
+$ cd jvwt
+$ ls
+48990 bsltmjz.nzp
+219604 ffpzc
+69573 mvmdfzr.lwb
+$ cd ..
+$ cd vwpqzdwh
+$ ls
+267581 pvcch
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd tbgjpphc
+$ ls
+255571 dstpcgr.tfq
+dir fdbwbrpp
+dir gjzwh
+dir hjvrtjt
+dir rhzczj
+292888 sgwz.cdz
+dir wlzhr
+149395 wnfzrqgz.dtn
+$ cd fdbwbrpp
+$ ls
+dir ffpzc
+dir qbrth
+51164 qprp
+dir slpt
+117026 sphbzn
+295685 vqgsglwq
+dir znmj
+$ cd ffpzc
+$ ls
+dir jhnzrdvb
+$ cd jhnzrdvb
+$ ls
+217775 ffpzc.sgw
+$ cd ..
+$ cd ..
+$ cd qbrth
+$ ls
+183969 lpbwgfjv.vcg
+47333 wjlmgq
+$ cd ..
+$ cd slpt
+$ ls
+32343 tqhtj.jwz
+$ cd ..
+$ cd znmj
+$ ls
+55058 mmnvqn.hqb
+$ cd ..
+$ cd ..
+$ cd gjzwh
+$ ls
+dir dvcbcd
+202530 dzdfc.vqq
+dir fsgz
+dir hfrrqq
+54897 jlzn.qsn
+16097 ldzqsbb.jzl
+225078 pswccrd
+dir rqqmldw
+292464 rzrdhbp.vld
+dir ssqbqqp
+dir zsztqrc
+$ cd dvcbcd
+$ ls
+187837 dzdfc.vqq
+dir jlwtvf
+dir jnjvshs
+164053 nrf.fqd
+5665 tlp.jmt
+13801 wjlmgq
+$ cd jlwtvf
+$ ls
+219985 sphbzn.dvj
+$ cd ..
+$ cd jnjvshs
+$ ls
+dir bsltmjz
+dir nrpm
+$ cd bsltmjz
+$ ls
+152972 qgdqj
+$ cd ..
+$ cd nrpm
+$ ls
+18509 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fsgz
+$ ls
+224576 mmnvqn.hqb
+$ cd ..
+$ cd hfrrqq
+$ ls
+dir bwgsnfvb
+dir fcsjl
+294608 ffpzc.gvm
+136880 qjcgtw
+dir sphbzn
+$ cd bwgsnfvb
+$ ls
+29735 dzdfc.vqq
+dir wstmzfml
+$ cd wstmzfml
+$ ls
+158447 bnvhbvvc.nrt
+59889 jclclgd
+$ cd ..
+$ cd ..
+$ cd fcsjl
+$ ls
+138297 ffpzc.szw
+$ cd ..
+$ cd sphbzn
+$ ls
+dir wqdths
+$ cd wqdths
+$ ls
+8326 cgvtw.jpz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd rqqmldw
+$ ls
+226757 dzdfc.vqq
+115055 mwb.btc
+dir qpts
+298524 sgwz.cdz
+$ cd qpts
+$ ls
+60860 bsltmjz.frp
+dir fcsjl
+94904 sgwz.cdz
+dir wnmqqspz
+$ cd fcsjl
+$ ls
+25082 mmnvqn.hqb
+$ cd ..
+$ cd wnmqqspz
+$ ls
+165529 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ssqbqqp
+$ ls
+192477 pvrgm
+$ cd ..
+$ cd zsztqrc
+$ ls
+254053 lht.htn
+$ cd ..
+$ cd ..
+$ cd hjvrtjt
+$ ls
+189942 fwps
+$ cd ..
+$ cd rhzczj
+$ ls
+36502 bmtfr
+dir ffjz
+35148 nctfhmzm.vsz
+dir qdgjzcz
+208196 rwql
+79863 sgwz.cdz
+dir snjntth
+$ cd ffjz
+$ ls
+dir grsvhwm
+$ cd grsvhwm
+$ ls
+50231 fwj.rdv
+dir snjntth
+$ cd snjntth
+$ ls
+dir dtbgb
+$ cd dtbgb
+$ ls
+150245 vdflm.lmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qdgjzcz
+$ ls
+222389 dzdfc.vqq
+$ cd ..
+$ cd snjntth
+$ ls
+56794 mmnvqn.hqb
+$ cd ..
+$ cd ..
+$ cd wlzhr
+$ ls
+116628 bsltmjz
+60122 jqpbsgnr.fgb
+252605 lfss
+300065 qwjdl.vhr
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd pwtpltr
+$ ls
+dir dplsvrhl
+140951 gwtfzqvd.znb
+dir jbvdb
+dir jst
+dir qhjv
+dir snjntth
+$ cd dplsvrhl
+$ ls
+272101 fcsjl
+dir ffpzc
+58852 mmnvqn.hqb
+dir mnhntjz
+91899 sgwz.cdz
+228077 snjntth.btv
+$ cd ffpzc
+$ ls
+5499 bsltmjz
+dir qmfwpjhl
+dir rsrb
+dir wgt
+$ cd qmfwpjhl
+$ ls
+300362 dzdfc.vqq
+$ cd ..
+$ cd rsrb
+$ ls
+252983 dzdfc.vqq
+107744 ltssrgqb.zvj
+214895 rhglgcwr.wpw
+249727 sgwz.cdz
+$ cd ..
+$ cd wgt
+$ ls
+141984 dzdfc.vqq
+194686 mmnvqn.hqb
+258023 pgr
+$ cd ..
+$ cd ..
+$ cd mnhntjz
+$ ls
+dir bdvght
+dir jprwchh
+dir snjntth
+$ cd bdvght
+$ ls
+243166 vpsvjdq.wsn
+$ cd ..
+$ cd jprwchh
+$ ls
+178943 bmpc.bjb
+$ cd ..
+$ cd snjntth
+$ ls
+dir nlbm
+dir zjmjntff
+$ cd nlbm
+$ ls
+33050 fcsjl.rcc
+dir sphbzn
+17446 wjlmgq
+$ cd sphbzn
+$ ls
+214563 prrfhff.pbp
+$ cd ..
+$ cd ..
+$ cd zjmjntff
+$ ls
+82134 sgwz.cdz
+52203 vrtlgdq.crp
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd jbvdb
+$ ls
+dir wmtjh
+$ cd wmtjh
+$ ls
+dir ggvwn
+$ cd ggvwn
+$ ls
+192285 spqvmf.sdh
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd jst
+$ ls
+dir bsltmjz
+212740 dzdfc.vqq
+dir gncztvtb
+dir jsqjcqnt
+286257 jvs
+36654 sdcsm.mbg
+192040 sgwz.cdz
+dir tbqphzb
+dir vdcqgts
+285843 wjlmgq
+$ cd bsltmjz
+$ ls
+215705 snjntth.gpv
+213665 wjlmgq
+$ cd ..
+$ cd gncztvtb
+$ ls
+229298 vqgsglwq
+$ cd ..
+$ cd jsqjcqnt
+$ ls
+dir bsltmjz
+dir fcsjl
+dir ffpzc
+dir sphbzn
+70864 vqgsglwq
+$ cd bsltmjz
+$ ls
+14981 pqzffzjc
+$ cd ..
+$ cd fcsjl
+$ ls
+140328 jwhczwbc
+$ cd ..
+$ cd ffpzc
+$ ls
+213650 mmnvqn.hqb
+$ cd ..
+$ cd sphbzn
+$ ls
+dir psmtphhq
+dir sphbzn
+$ cd psmtphhq
+$ ls
+dir ffpzc
+123131 tzgwd
+$ cd ffpzc
+$ ls
+49737 cfngvmd
+dir gcnrp
+172799 gmd.cwl
+dir llnztjf
+dir nbqs
+79661 rrqz
+$ cd gcnrp
+$ ls
+283 vqnrgl.vwp
+$ cd ..
+$ cd llnztjf
+$ ls
+63263 tjhm.bwh
+$ cd ..
+$ cd nbqs
+$ ls
+dir vssmq
+$ cd vssmq
+$ ls
+88980 dzdfc.vqq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd sphbzn
+$ ls
+20140 fcsjl.zrs
+260579 snjntth
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd tbqphzb
+$ ls
+93470 sgwz.cdz
+$ cd ..
+$ cd vdcqgts
+$ ls
+223564 dzdfc.vqq
+dir ffpzc
+dir gwhfgwf
+dir nbjtqnng
+dir snjntth
+$ cd ffpzc
+$ ls
+42813 qwwmw.nmt
+$ cd ..
+$ cd gwhfgwf
+$ ls
+59918 jvfv.mpm
+dir mjl
+211039 pcwl
+$ cd mjl
+$ ls
+13004 pgjb.tpq
+195995 tms.fjz
+$ cd ..
+$ cd ..
+$ cd nbjtqnng
+$ ls
+107058 dzdfc.vqq
+dir ldrsd
+111631 vqgsglwq
+104599 wbzmdljw.tjq
+155747 wjlmgq
+$ cd ldrsd
+$ ls
+107439 jvjm
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+242680 fgrt.gng
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qhjv
+$ ls
+dir bmnm
+68453 hjjpdgn.hwl
+dir sjlbj
+dir vqnrj
+$ cd bmnm
+$ ls
+1238 vqgsglwq
+$ cd ..
+$ cd sjlbj
+$ ls
+44239 wzzbtmrz.gml
+$ cd ..
+$ cd vqnrj
+$ ls
+3286 bsltmjz.qlc
+$ cd ..
+$ cd ..
+$ cd snjntth
+$ ls
+130833 blm.wmt
+dir snjntth
+dir tcnmbcgg
+218869 wjlmgq
+$ cd snjntth
+$ ls
+dir snmrdfbt
+$ cd snmrdfbt
+$ ls
+281025 bzrsds.lfg
+$ cd ..
+$ cd ..
+$ cd tcnmbcgg
+$ ls
+194998 fcsjl
+dir qdrmpqgn
+dir rzqd
+dir tcsds
+$ cd qdrmpqgn
+$ ls
+165713 qmzgt.tnc
+$ cd ..
+$ cd rzqd
+$ ls
+dir cwhnmlv
+57819 fcsjl
+246864 pjnzdvd.gjm
+$ cd cwhnmlv
+$ ls
+287539 mmnvqn.hqb
+215636 pbnjt.zbn
+124638 sqd
+$ cd ..
+$ cd ..
+$ cd tcsds
+$ ls
+78812 gfmgb.wqj
+218987 hnhfvz.dln
+209640 mzzhqlq.zqp
+102492 nml.ppg
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd szn
+$ ls
+dir fcsjl
+dir snjntth
+dir zjbp
+$ cd fcsjl
+$ ls
+158019 jsv.pmz
+$ cd ..
+$ cd snjntth
+$ ls
+229510 dfvpvp
+191061 fgplbptq.jlt
+dir lfb
+234911 lfsrwr.wcb
+dir lrfcgzl
+48031 stbbw
+219691 vqgsglwq
+dir zshh
+$ cd lfb
+$ ls
+dir btj
+99591 dhrjbvvg.gwm
+137224 dzdfc.vqq
+201972 jtzmqsvj.wnd
+9704 mmnvqn.hqb
+dir pwg
+200308 snjntth.css
+dir wcmhcfm
+dir zwhvmln
+$ cd btj
+$ ls
+dir rnbzdfgn
+51799 wdhsm
+dir wvf
+$ cd rnbzdfgn
+$ ls
+117095 bsltmjz.tlv
+$ cd ..
+$ cd wvf
+$ ls
+dir ffpzc
+dir ncbmgpsc
+dir wtwrmjnt
+$ cd ffpzc
+$ ls
+249919 lsth.fmf
+$ cd ..
+$ cd ncbmgpsc
+$ ls
+147899 dzdfc.vqq
+$ cd ..
+$ cd wtwrmjnt
+$ ls
+252366 pvpdv.jwz
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd pwg
+$ ls
+280845 fcsjl.fjz
+44300 sgwz.cdz
+dir snjntth
+229605 vqgsglwq
+$ cd snjntth
+$ ls
+2053 pflvsnzs
+143522 sgwz.cdz
+$ cd ..
+$ cd ..
+$ cd wcmhcfm
+$ ls
+229329 qsznhwlw.vjg
+$ cd ..
+$ cd zwhvmln
+$ ls
+dir ffpzc
+dir tjjzbf
+dir wzcq
+$ cd ffpzc
+$ ls
+dir ncnj
+37497 vqgsglwq
+$ cd ncnj
+$ ls
+40920 htbjhjq
+$ cd ..
+$ cd ..
+$ cd tjjzbf
+$ ls
+47522 mczn.spd
+$ cd ..
+$ cd wzcq
+$ ls
+56662 ffpzc.vwp
+dir snjntth
+$ cd snjntth
+$ ls
+117276 wjlmgq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd lrfcgzl
+$ ls
+267485 rsjmpph.qqz
+$ cd ..
+$ cd zshh
+$ ls
+dir ffpzc
+dir gmn
+dir snjntth
+150048 tgtlh
+32020 thfr
+72152 vqgsglwq
+$ cd ffpzc
+$ ls
+dir snjntth
+$ cd snjntth
+$ ls
+224945 dpfpz
+$ cd ..
+$ cd ..
+$ cd gmn
+$ ls
+238996 sgwz.cdz
+$ cd ..
+$ cd snjntth
+$ ls
+86775 dzdfc.vqq
+19560 vshcmjj
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd zjbp
+$ ls
+dir fcsjl
+41522 nlvpb.fpf
+dir nmtjtd
+$ cd fcsjl
+$ ls
+276802 fcsjl.psm
+197934 sgwz.cdz
+$ cd ..
+$ cd nmtjtd
+$ ls
+47477 dvqmqlgw.ths
+51081 vqgsglwq
diff --git a/day07b/examples/test.txt b/day07b/examples/test.txt
new file mode 100644
index 0000000..09a921e
--- /dev/null
+++ b/day07b/examples/test.txt
@@ -0,0 +1,23 @@
+$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k
diff --git a/day07b/src/main.rs b/day07b/src/main.rs
new file mode 100644
index 0000000..f9cd74c
--- /dev/null
+++ b/day07b/src/main.rs
@@ -0,0 +1,268 @@
+/// --- Part Two ---
+///
+/// Now, you're ready to choose a directory to delete.
+///
+/// The total disk space available to the filesystem is 70000000.  To run the update, you need
+/// unused space of at least 30000000.  You need to find a directory you can delete that will free
+/// up enough space to run the update.
+///
+/// In the example above, the total size of the outermost directory (and thus the total amount of
+/// used space) is 48381165; this means that the size of the unused space must currently be
+/// 21618835, which isn't quite the 30000000 required by the update.  Therefore, the update still
+/// requires a directory with total size of at least 8381165 to be deleted before it can run.
+///
+/// To achieve this, you have the following options:
+///
+///     Delete directory e, which would increase unused space by 584.
+///     Delete directory a, which would increase unused space by 94853.
+///     Delete directory d, which would increase unused space by 24933642.
+///     Delete directory /, which would increase unused space by 48381165.
+///
+/// Directories e and a are both too small; deleting them would not free up enough space. However,
+/// directories d and / are both big enough!  Between these, choose the smallest: d, increasing
+/// unused space by 24933642.
+///
+/// Find the smallest directory that, if deleted, would free up enough space on the filesystem to
+/// run the update.  What is the total size of that directory?
+use clap::Parser;
+use nom::branch::alt;
+use nom::bytes::streaming::tag;
+use nom::character::streaming::{char, newline, not_line_ending, space1, u64};
+use nom::combinator::{map, peek};
+use nom::error::{context, ContextError, ErrorKind as NomErrorKind, ParseError};
+use nom::multi::many_till;
+use nom::sequence::{delimited, preceded, terminated, tuple};
+use nom::IResult;
+
+use std::collections::HashMap;
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::BufReader;
+use std::iter::*;
+use std::path::PathBuf;
+
+pub type Input<'a> = &'a str;
+pub type Result<'a, T> = IResult<Input<'a>, T, Error<Input<'a>>>;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ErrorKind {
+    Nom(NomErrorKind),
+    Context(&'static str),
+    Custom(String),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Error<I> {
+    pub errors: Vec<(I, ErrorKind)>,
+}
+
+impl<I> ParseError<I> for Error<I> {
+    fn from_error_kind(input: I, kind: NomErrorKind) -> Self {
+        let errors = vec![(input, ErrorKind::Nom(kind))];
+        Self { errors }
+    }
+
+    fn append(input: I, kind: NomErrorKind, mut other: Self) -> Self {
+        other.errors.push((input, ErrorKind::Nom(kind)));
+        other
+    }
+}
+
+impl<I> ContextError<I> for Error<I> {
+    fn add_context(input: I, ctx: &'static str, mut other: Self) -> Self {
+        other.errors.push((input, ErrorKind::Context(ctx)));
+        other
+    }
+}
+
+const FILEPATH: &'static str = "examples/input.txt";
+const EOF_CHAR: char = '\0';
+const TOTALSPACE: u64 = 70000000;
+const NEEDEDSPACE: u64 = 30000000;
+
+#[derive(Parser, Debug)]
+#[clap(author, version, about, long_about = None)]
+struct Cli {
+    #[clap(short, long, default_value = FILEPATH)]
+    file: PathBuf,
+}
+
+#[derive(Clone, Debug)]
+enum Commands {
+    ChangeDir(String),
+    List(Vec<ListEntry>),
+}
+
+#[derive(Clone, Debug)]
+enum ListEntry {
+    File(FileEntry),
+    Folder(String),
+}
+
+#[derive(Clone, Debug)]
+struct FileEntry {
+    name: String,
+    size: u64,
+}
+
+#[derive(Clone, Debug)]
+struct Arena(Vec<Node>);
+
+#[derive(Clone, Debug)]
+struct Node {
+    size: u64,
+    parent: Option<usize>,
+    children: HashMap<String, usize>,
+}
+
+impl Node {
+    fn new() -> Self {
+        Node {
+            size: 0,
+            parent: None,
+            children: HashMap::new(),
+        }
+    }
+
+    fn with_parent(idx: usize) -> Self {
+        Node {
+            size: 0,
+            parent: Some(idx),
+            children: HashMap::new(),
+        }
+    }
+}
+
+impl Arena {
+    // NOTE: only call this once per node
+    fn consume(&mut self, idx: usize, ls: Vec<ListEntry>) {
+        for le in ls.into_iter() {
+            match le {
+                ListEntry::File(f) => {
+                    let mut iteridx = idx;
+                    loop {
+                        self.0[iteridx].size += f.size;
+                        iteridx = if let Some(pidx) = self.0[iteridx].parent {
+                            pidx
+                        } else {
+                            break;
+                        };
+                    }
+                }
+                ListEntry::Folder(f) => {
+                    let fidx = self.0.len();
+                    self.0.push(Node::with_parent(idx));
+                    self.0[idx].children.insert(f, fidx);
+                }
+            }
+        }
+    }
+
+    fn get(&mut self, idx: usize) -> &mut Node {
+        &mut self.0[idx]
+    }
+}
+
+fn parse_cd(input: &str) -> Result<Commands> {
+    context(
+        "parse_cd",
+        map(
+            delimited(tuple((tag("cd"), space1)), not_line_ending, newline),
+            |s: &str| Commands::ChangeDir(s.to_string()),
+        ),
+    )(input)
+}
+
+fn end_of_file_or_ls(input: &str) -> Result<char> {
+    alt((char(EOF_CHAR), peek(char('$'))))(input)
+}
+
+fn parse_ls(input: &str) -> Result<Commands> {
+    let (input, _) = context("parse_ls", terminated(tag("ls"), newline))(input)?;
+    let (input, (lsv, _)) = many_till(parse_ls_entry, end_of_file_or_ls)(input)?;
+    Ok((input, Commands::List(lsv)))
+}
+
+fn parse_ls_entry(input: &str) -> Result<ListEntry> {
+    context("parse_ls_entry", alt((parse_file, parse_folder)))(input)
+}
+
+fn parse_file(input: &str) -> Result<ListEntry> {
+    map(
+        terminated(tuple((u64, preceded(tag(" "), not_line_ending))), newline),
+        |(size, name): (u64, &str)| {
+            ListEntry::File(FileEntry {
+                name: name.to_string(),
+                size,
+            })
+        },
+    )(input)
+}
+
+fn parse_folder(input: &str) -> Result<ListEntry> {
+    map(
+        delimited(tag("dir "), not_line_ending, newline),
+        |s: &str| ListEntry::Folder(s.to_string()),
+    )(input)
+}
+
+fn parse_cmd(input: &str) -> Result<Commands> {
+    context(
+        "parse_cmd",
+        preceded(tuple((tag("$"), space1)), alt((parse_cd, parse_ls))),
+    )(input)
+}
+
+fn main() {
+    let args = Cli::parse();
+
+    let file = File::open(&args.file).unwrap();
+    let mut reader = BufReader::new(file);
+
+    let mut buf = String::new();
+    let mut cmds = Vec::new();
+    'block: loop {
+        let len = reader.read_line(&mut buf).unwrap();
+        if len == 0 {
+            buf.push(EOF_CHAR);
+        }
+        loop {
+            match parse_cmd(buf.as_str()) {
+                Ok((input, cmd)) => {
+                    cmds.push(cmd);
+                    if len == 0 && input.len() == 0 {
+                        break 'block;
+                    }
+                    let _ = buf.drain(..(buf.len() - input.len()));
+                }
+                Err(err) => match err {
+                    nom::Err::Incomplete(_) => continue 'block,
+                    e @ _ => panic!("buf={} err={}", buf, e),
+                },
+            }
+        }
+    }
+
+    let mut loc = 0;
+    let mut arena = Arena(Vec::new());
+    arena.0.push(Node::new());
+    for cmd in cmds.into_iter() {
+        match cmd {
+            Commands::ChangeDir(dir) => match dir.as_str() {
+                "/" => loc = 0,
+                ".." => loc = arena.get(loc).parent.unwrap(),
+                _ => loc = arena.get(loc).children[&dir],
+            },
+            Commands::List(lsv) => arena.consume(loc, lsv),
+        }
+    }
+
+    let rmdir_minsize = NEEDEDSPACE - (TOTALSPACE - arena.get(0).size);
+    let res: u64 = arena
+        .0
+        .into_iter()
+        .filter(|n| n.size >= rmdir_minsize)
+        .map(|n| n.size)
+        .min().unwrap();
+    println!("{res:?}");
+}