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#![feature(binary_heap_into_iter_sorted)]
/// --- Day 1: Calorie Counting ---
///
/// Santa's reindeer typically eat regular reindeer food, but they need a lot of magical energy to
/// deliver presents on Christmas. For that, their favourite snack is a special type of star fruit
/// that only grows deep in the jungle. The Elves have brought you on their annual expedition to
/// the grove where the fruit grows.
///
/// To supply enough magical energy, the expedition needs to retrieve a minimum of fifty stars by
/// December 25th. Although the Elves assure you that the grove has plenty of fruit, you decide to
/// grab any fruit you see along the way, just in case.
///
/// Collect stars by solving puzzles. Two puzzles will be made available on each day in the Advent
/// calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants one
/// star. Good luck!
///
/// The jungle must be too overgrown and difficult to navigate in vehicles or access from the air;
/// the Elves' expedition traditionally goes on foot. As your boats approach land, the Elves begin
/// taking inventory of their supplies. One important consideration is food - in particular, the
/// number of Calories each Elf is carrying (your puzzle input).
///
/// The Elves take turns writing down the number of Calories contained by the various meals,
/// snacks, rations, etc. that they've brought with them, one item per line. Each Elf separates
/// their own inventory from the previous Elf's inventory (if any) by a blank line.
///
/// For example, suppose the Elves finish writing their items' Calories and end up with the
/// following list:
///
/// ```
/// 1000
/// 2000
/// 3000
///
/// 4000
///
/// 5000
/// 6000
///
/// 7000
/// 8000
/// 9000
///
/// 10000
/// ```
///
/// This list represents the Calories of the food carried by five Elves:
///
/// The first Elf is carrying food with 1000, 2000, and 3000 Calories, a total of 6000 Calories.
/// The second Elf is carrying one food item with 4000 Calories.
/// The third Elf is carrying food with 5000 and 6000 Calories, a total of 11000 Calories.
/// The fourth Elf is carrying food with 7000, 8000, and 9000 Calories, a total of 24000 Calories.
/// The fifth Elf is carrying one food item with 10000 Calories.
///
/// In case the Elves get hungry and need extra snacks, they need to know which Elf to ask: they'd
/// like to know how many Calories are being carried by the Elf carrying the most Calories. In the
/// example above, this is 24000 (carried by the fourth Elf).
///
/// Find the Elf carrying the most Calories. How many total Calories is that Elf carrying?
use clap::Parser;
use std::collections::BinaryHeap;
use std::fs::File;
use std::io::prelude::*;
use std::io::BufReader;
use std::path::PathBuf;
const FILEPATH: &'static str = "examples/input.txt";
#[derive(Parser, Debug)]
#[clap(author, version, about, long_about = None)]
struct Cli {
#[clap(short, long, default_value = FILEPATH)]
file: PathBuf,
}
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
struct CalorieCount {
elf: usize,
calories: usize,
}
impl PartialOrd for CalorieCount {
fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
Some(self.cmp(other))
}
}
impl Ord for CalorieCount {
fn cmp(&self, other: &Self) -> std::cmp::Ordering {
self.calories.cmp(&other.calories)
}
}
fn main() {
let args = Cli::parse();
let file = File::open(&args.file).unwrap();
let mut reader = BufReader::new(file);
let mut heap = BinaryHeap::new();
let mut line = String::new();
let mut calorie_count = CalorieCount {
elf: 1,
calories: 0,
};
while let Ok(bytes) = reader.read_line(&mut line) {
// EOF
if bytes == 0 {
heap.push(calorie_count);
break;
}
// Newlines
let tline = line.trim();
if tline.is_empty() {
// Push onto the binary heap
heap.push(calorie_count);
calorie_count.calories = 0;
calorie_count.elf += 1;
continue;
}
// Parse the calories
let calories = tline.parse::<usize>().unwrap();
// Accumulate the calorie count for this elf
calorie_count.calories += calories;
// Clear the line for the next iteration
line.clear();
}
// Find the elf carrying the most calories
let res = heap.peek().unwrap();
println!(
"The most amount of calories carried by an elf is {} and is carried by elf {}",
res.calories, res.elf
);
let _ = heap
.into_iter_sorted()
.inspect(|x| println!("calories={:6} elf={}", x.calories, x.elf))
.take(10)
.last();
println!(
"{}",
include_str!("../examples/input.txt")
.split("\n\n")
.map(|e| e.lines().map(|c| c.parse::<u32>().unwrap()).sum::<u32>())
.max()
.unwrap()
);
}
|
