day 9 part 1

Author: mflinn-broad

src/days/day8.rs

@@ -130,3 +130,28 @@ fn part_2(input: &Vec<(Vec<&str>, Vec<&str>)>) -> u32 {
         })
         .sum()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    extern crate test;
+    use test::Bencher;
+
+    #[bench]
+    fn bench_part_1(b: &mut Bencher) {
+        let raw_input = util::read_input("inputs/day8.txt").unwrap();
+        b.iter(|| {
+            let mut input = process(&raw_input);
+            part_1(&mut input);
+        });
+    }
+
+    #[bench]
+    fn bench_part_2(b: &mut Bencher) {
+        let raw_input = util::read_input("inputs/day8.txt").unwrap();
+        b.iter(|| {
+            let input = process(&raw_input);
+            part_2(&input);
+        });
+    }
+}

src/days/day9.rs

@@ -0,0 +1,53 @@
+use crate::util;
+
+pub fn run() {
+    let raw_input = util::read_input("inputs/day9.txt").unwrap();
+    let input = process(&raw_input);
+    println!("Part 1: {:?}", part_1(&input));
+}
+
+pub fn process(input: &str) -> Vec<Vec<u8>> {
+    input
+        .lines()
+        .map(|line| {
+            line.trim()
+                .chars()
+                .map(|num| num.to_string().parse().unwrap())
+                .collect()
+        })
+        .collect()
+}
+
+fn is_local_minima(target: u8, adjacents: Vec<u8>) -> bool {
+    adjacents.iter()
+        .all(|val| target < *val)
+}
+
+fn part_1(input: &Vec<Vec<u8>>) -> u32 {
+    input.iter()
+        .enumerate()
+        .fold(0, |risk_score, (row_idx, row)| {
+            risk_score + row.iter()
+                .enumerate()
+                .fold(0, |row_risk, (col, height)| {
+                    let mut adjacents: Vec<u8> = Vec::new();
+                    if row_idx != 0 {
+                        adjacents.push(input[row_idx - 1][col]);
+                    }
+                    if col != 0 {
+                        adjacents.push(input[row_idx][col - 1]);
+                    }
+                    if row_idx != (input.len() - 1) {
+                        adjacents.push(input[row_idx + 1][col]);
+                    }
+                    if col != (input[0].len() - 1) {
+                        adjacents.push(input[row_idx][col + 1]);
+                    }
+                    if is_local_minima(*height, adjacents) {
+                        row_risk + (*height as u32) + 1
+                    } else {
+                        row_risk
+                    }
+                })
+        })
+}

src/days/mod.rs

@@ -6,3 +6,4 @@ pub mod day5;
 pub mod day6;
 pub mod day7;
 pub mod day8;
+pub mod day9;

src/main.rs

@@ -17,4 +17,6 @@ fn main() {
     day7::run();
     println!("Day 8 --------");
     day8::run();
+    println!("Day 9 ---------");
+    day9::run();
 }