Day 2, 3, and 4.

2017/02/src/main.rs

@@ -0,0 +1,89 @@
+use std::io::{self, Read};
+
+
+type Data = Vec<Vec<u32>>;
+
+
+fn parse(input: &str) -> Data {
+    input
+        .lines()
+        .map(|line| {
+            line.split_whitespace()
+                .flat_map(|cell| cell.parse::<u32>())
+                .collect::<Vec<_>>()
+        })
+        .collect::<Vec<_>>()
+}
+
+fn checksum(data: &Data) -> u32 {
+    data.iter()
+        .map(|row| {
+            let max = row.iter().max().unwrap_or(&0);
+            let min = row.iter().min().unwrap_or(&0);
+
+            max - min
+        })
+        .sum()
+}
+
+fn divisible(data: &Data) -> u32 {
+    data.iter()
+        .map(|row| {
+            let mut iter = row.iter();
+
+            while let Some(a) = iter.next() {
+                for b in iter.clone() {
+                    if a % b == 0 {
+                        return a / b;
+                    } else if b % a == 0 {
+                        return b / a;
+                    }
+                }
+            }
+
+            0
+        })
+        .sum()
+}
+
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin()
+        .read_to_string(&mut input)
+        .expect("failed to parse input");
+
+    let data = parse(&input);
+
+    println!("checksum={}", checksum(&data));
+    println!("divisible={}", divisible(&data));
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_checksum() {
+        let input = "5 1 9 5\n\
+                     7 5 3\n\
+                     2 4 6 8";
+
+        let data = parse(input);
+
+        assert_eq!(checksum(&data), 18);
+    }
+
+    #[test]
+    fn test_divisible() {
+        let input = "5 9 2 8\n\
+                     9 4 7 3\n\
+                     3 8 6 5";
+
+        let data = parse(input);
+
+        assert_eq!(divisible(&data), 9);
+    }
+}