mirror of
https://github.com/Ajetski/advent-of-code.git
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130 lines
3.4 KiB
Rust
130 lines
3.4 KiB
Rust
/**
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* File: day09.rs
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* Author: Adam Jeniski; @Ajetski
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*/
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use std::collections::{HashSet, LinkedList};
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type Position = (usize, usize);
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fn is_local_min(data: &Vec<Vec<u64>>, (row, col): Position) -> bool {
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if row > 0 && data[row][col] >= data[row - 1][col] {
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return false;
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} else if row < data.len() - 1 && data[row][col] >= data[row + 1][col] {
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return false;
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} else if col > 0 && data[row][col] >= data[row][col - 1] {
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return false;
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} else if col < data[row].len() - 1 && data[row][col] >= data[row][col + 1] {
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return false;
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}
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true
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}
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fn get_local_mins(data: &Vec<Vec<u64>>) -> Vec<Position> {
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let mut mins = vec![];
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for row in 0..data.len() {
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for col in 0..data[row].len() {
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if is_local_min(data, (row, col)) {
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mins.push((row, col));
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}
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}
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}
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mins
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}
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/** use a BFS to count all of the nodes in the basin */
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fn get_basin_size_from_min(data: &Vec<Vec<u64>>, start: Position) -> u64 {
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/* queue: pop from front; push to back */
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let mut search_queue = LinkedList::from([start]);
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let mut visited = HashSet::from([start]);
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let mut count = 1;
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while !search_queue.is_empty() {
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let (row, col) = search_queue.pop_front().unwrap();
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let mut directions = vec![];
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if row > 0 {
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directions.push((row - 1, col));
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}
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if col > 0 {
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directions.push((row, col - 1));
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}
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if row < data.len() - 1 {
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directions.push((row + 1, col));
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}
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if col < data[row].len() - 1 {
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directions.push((row, col + 1));
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}
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for (next_row, next_col) in directions {
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if data[next_row][next_col] != 9 && !visited.contains(&(next_row, next_col)) {
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search_queue.push_back((next_row, next_col));
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count += 1;
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}
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visited.insert((next_row, next_col));
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}
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}
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count
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}
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fn parse_input(input: &str) -> Vec<Vec<u64>> {
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input
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.split_ascii_whitespace()
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.map(|a| a.chars().map(|c| c.to_string().parse().unwrap()).collect())
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.collect()
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}
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fn part_1_solution(input: &str) -> u64 {
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let data = parse_input(input);
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let mins = get_local_mins(&data);
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mins.len() as u64
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+ mins.iter().fold(0, |acc, (row, col)| {
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acc + data[row.to_owned()][col.to_owned()]
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})
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}
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fn part_2_solution(input: &str) -> u64 {
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let data = parse_input(input);
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let mins = get_local_mins(&data);
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let mut basin_sizes: Vec<u64> = mins
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.iter()
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.map(|k| get_basin_size_from_min(&data, k.to_owned()))
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.collect();
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basin_sizes.sort();
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basin_sizes.reverse();
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basin_sizes.iter().take(3).fold(1, |prod, curr| prod * curr)
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}
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#[cfg(test)]
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mod part1 {
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use super::*;
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#[test]
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fn run_sample() {
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let input = include_str!("../inputs/9_test.txt");
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assert_eq!(part_1_solution(input), 15);
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}
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#[test]
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fn run() {
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let input = include_str!("../inputs/9.txt");
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assert_eq!(part_1_solution(input), 502);
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}
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}
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#[cfg(test)]
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mod part2 {
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use super::*;
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#[test]
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fn run_sample() {
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let input = include_str!("../inputs/9_test.txt");
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assert_eq!(part_2_solution(input), 1134);
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}
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#[test]
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fn run() {
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let input = include_str!("../inputs/9.txt");
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assert_eq!(part_2_solution(input), 1330560);
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}
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}
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