116 lines
2.8 KiB
Rust
116 lines
2.8 KiB
Rust
#[derive(Clone, Copy, Debug)]
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enum Order {
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Increasing,
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Decreasing,
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}
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pub fn process_part1(input: &str) -> i32 {
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let mut safe = 0;
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input.lines().for_each(|line| {
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let levels = line
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.split_whitespace()
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.map(|e| e.parse::<i32>().unwrap())
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.collect::<Vec<i32>>();
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if is_safe(levels) {
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safe += 1;
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}
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});
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safe
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}
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pub fn process_part2(input: &str) -> i32 {
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let mut safe = 0;
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input.lines().for_each(|line| {
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let levels = line
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.split_whitespace()
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.map(|e| e.parse::<i32>().unwrap())
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.collect::<Vec<i32>>();
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if is_safe(levels.clone()) {
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safe += 1;
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} else {
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for idx in 0..levels.len() {
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let mut new_levels = levels.clone();
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new_levels.remove(idx);
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if is_safe(new_levels) {
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safe += 1;
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break;
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}
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}
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}
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});
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safe
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}
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fn is_safe(levels: Vec<i32>) -> bool {
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let mut order = None;
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let mut is_safe = true;
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for level_pair in levels.windows(2) {
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let difference = level_pair[0] - level_pair[1];
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let new_order = match difference.cmp(&0) {
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std::cmp::Ordering::Less => Some(Order::Increasing),
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std::cmp::Ordering::Equal => None,
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std::cmp::Ordering::Greater => Some(Order::Decreasing),
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};
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let difference = difference.abs();
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if difference == 0 {
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is_safe = false;
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break;
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}
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match (order, new_order) {
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(None, Some(new_order)) => {
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if difference <= 3 {
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order = Some(new_order);
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} else {
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is_safe = false;
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break;
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}
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}
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(Some(Order::Increasing), Some(Order::Decreasing))
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| (Some(Order::Decreasing), Some(Order::Increasing)) => {
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is_safe = false;
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break;
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}
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(None, None)
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| (Some(_), None)
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| (Some(Order::Increasing), Some(Order::Increasing))
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| (Some(Order::Decreasing), Some(Order::Decreasing)) => {
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if difference > 3 {
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is_safe = false;
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break;
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}
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}
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};
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}
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if is_safe {
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true
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//println!("line {line} is safe");
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} else {
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false
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//println!("line {line} is unsafe");
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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const INPUT: &str = "7 6 4 2 1
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1 2 7 8 9
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9 7 6 2 1
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1 3 2 4 5
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8 6 4 4 1
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1 3 6 7 9";
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#[test]
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fn part1() {
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let result = process_part1(INPUT);
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assert_eq!(result, 2);
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}
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#[test]
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fn part2() {
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let result = process_part2(INPUT);
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assert_eq!(result, 4);
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}
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}
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