day 2 part 1

src/day02.rs

@@ -1,17 +1,49 @@
 use std::fs::read_to_string;
 
+use itertools::Itertools;
+
 pub fn day_main() {
-    let input = read_to_string("input/day01.txt").unwrap();
+    let input = read_to_string("input/day02.txt").unwrap();
     println!("part1: {}", part1(&input));
     // println!("part2: {}", part2(&input));
 }
 
-type Int = i32;
+fn part1(input: &str) -> usize {
+    input
+        .lines()
+        .map(|line| {
+            line.split_whitespace()
+                .map(|s| s.parse::<i32>().unwrap())
+                .collect_vec()
+        })
+        .filter(|report: &Vec<i32>| {
+            let pairs = report
+                .windows(2)
+                .map(|window| window[1] - window[0])
+                .collect_vec();
+            let steepest_slope = pairs.iter().map(|x| x.abs()).max().unwrap();
+            let lowest_slope = pairs.iter().map(|x| x.abs()).min().unwrap();
+            let same_sign = pairs.iter().map(|x| x.signum()).unique().count() == 1;
+            println!("{:?} - {steepest_slope}/{same_sign}", report);
 
-fn part1(input: &str) -> Int {
-    0
+            steepest_slope <= 3 && lowest_slope >= 1 && same_sign
+        })
+        .count()
 }
 
 // fn part2(input: &str) -> Int {
 //     0
 // }
+#[cfg(test)]
+mod test {
+    #[test]
+    fn part1() {
+        let input = r"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";
+        assert_eq!(2, super::part1(input));
+    }
+}