day 2

Cargo.toml

@@ -24,6 +24,7 @@ test_lib = []
 # Template dependencies
 chrono = { version = "0.4.38", optional = true }
 dhat = { version = "0.3.3", optional = true }
+itertools = "0.13.0"
 pico-args = "0.5.0"
 tinyjson = "2.5.1"
 

README.md

@@ -13,13 +13,12 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 <!--- advent_readme_stars table --->
 
 <!--- benchmarking table --->
-
 ## Benchmarks
 
-|           Day            |  Part 1  |  Part 2  |
-| :----------------------: | :------: | :------: |
+| Day | Part 1 | Part 2 |
+| :---: | :---: | :---:  |
 | [Day 1](./src/bin/01.rs) | `40.7µs` | `58.2µs` |
+| [Day 2](./src/bin/02.rs) | `117.1µs` | `205.3µs` |
 
-**Total: 0.10ms**
-
+**Total: 0.42ms**
 <!--- benchmarking table --->

data/examples/02.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

src/bin/02.rs

@@ -1,11 +1,109 @@
+use std::collections::VecDeque;
+
+use itertools::Itertools;
+
 advent_of_code::solution!(2);
 
 pub fn part_one(input: &str) -> Option<u32> {
-    None
+    let reports = input
+        .lines()
+        .map(|line| {
+            line.split(" ")
+                .map(|a| a.parse::<i32>().unwrap())
+                .collect_vec()
+        })
+        .collect_vec();
+
+    let mut bad_reports = 0;
+    for report in reports.iter() {
+        let mut dir = 0;
+        for idx in 0..report.len() - 1 {
+            let l = report.get(idx).unwrap();
+            let r = report.get(idx + 1).unwrap();
+            match r.cmp(l) {
+                std::cmp::Ordering::Less => {
+                    if dir == 1 || l - r > 3 {
+                        bad_reports += 1;
+                        break;
+                    }
+                    dir = -1;
+                }
+                std::cmp::Ordering::Equal => {
+                    bad_reports += 1;
+                    break;
+                }
+                std::cmp::Ordering::Greater => {
+                    if dir == -1 || r - l > 3 {
+                        bad_reports += 1;
+                        break;
+                    }
+                    dir = 1;
+                }
+            }
+        }
+    }
+    Some((reports.len() - bad_reports) as u32)
 }
 
 pub fn part_two(input: &str) -> Option<u32> {
-    None
+    let reports = input
+        .lines()
+        .map(|line| {
+            line.split(" ")
+                .map(|a| a.parse::<i32>().unwrap())
+                .collect_vec()
+        })
+        .collect_vec();
+
+    let mut good_reports = 0;
+    for report in reports.iter() {
+        let mut to_check_queue = VecDeque::new();
+        to_check_queue.push_back(report);
+        while !to_check_queue.is_empty() {
+            if is_safe(report) {
+                good_reports += 1
+            } else {
+                for idx in 0..report.len() {
+                    let mut new_report = report.clone();
+                    new_report.remove(idx);
+                    if is_safe(&new_report) {
+                        good_reports += 1;
+                        break;
+                    }
+                }
+            };
+
+            to_check_queue.pop_front();
+        }
+    }
+
+    Some(good_reports)
+}
+
+fn is_safe(report: &[i32]) -> bool {
+    let mut dir = 0;
+    for idx in 0..report.len() - 1 {
+        let l = report.get(idx).unwrap();
+        let r = report.get(idx + 1).unwrap();
+        match r.cmp(l) {
+            std::cmp::Ordering::Less => {
+                if dir == 1 || l - r > 3 {
+                    return false;
+                }
+                dir = -1;
+            }
+            std::cmp::Ordering::Equal => {
+                return false;
+            }
+            std::cmp::Ordering::Greater => {
+                if dir == -1 || r - l > 3 {
+                    return false;
+                }
+                dir = 1;
+            }
+        }
+    }
+    true
 }
 
 #[cfg(test)]
@@ -15,12 +113,12 @@ mod tests {
     #[test]
     fn test_part_one() {
         let result = part_one(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some(2));
     }
 
     #[test]
     fn test_part_two() {
         let result = part_two(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some(4));
     }
 }