37 lines
1.3 KiB
Rust
37 lines
1.3 KiB
Rust
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use std::collections::HashMap;
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fn main() {
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let input = include_str!("input.txt");
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let mut stones = input
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.split(' ')
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.map(|s| (s.parse::<u64>().unwrap(), 1u64))
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.collect::<HashMap<u64, u64>>();
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for _ in 1..=75 {
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let mut new_stones = HashMap::<u64, u64>::new();
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for stone in stones.keys() {
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if *stone == 0 {
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// Take all zeroes, and move them to ones
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new_stones.insert(1, new_stones.get(&1).unwrap_or(&0) + stones[&0]);
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} else {
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let digits = stone.ilog10() + 1;
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if digits % 2 == 0 {
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let new_rock = stone / 10u64.pow(digits / 2);
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new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
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let new_rock = stone % 10u64.pow(digits / 2);
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new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
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} else {
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let new_rock = stone * 2024;
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new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
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}
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}
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}
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stones = new_stones;
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}
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println!("Result: {}", stones.into_values().sum::<u64>());
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}
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