add day 2 solution

src/bin/02.rs

@@ -0,0 +1,78 @@
+// scores a hand, where each item in the tuple is one player's throw (1 for rock, 2 for paper, 3 for scissors)
+fn score_hand(input: (u32,u32)) -> u32 {
+    let t = input.0; // them
+    let m = input.1; // me
+    let win_value = if t == m {
+    3
+    } else if (m == 1 && t ==3) || (m == 2 && t == 1) || (m == 3 && t == 2) { // if we win
+    6
+    } else {
+    0
+    };
+
+    input.1 + win_value
+}
+
+// generates a hand according to the rules, where the first item in the tuple is the opponent's throw and the second item is the desired result (win, draw, lose)
+fn play_hand(input: (u32, u32)) -> (u32,u32) {
+    let (t,r) = input;
+
+    if r == 2 { // rule: draw
+        (t,t)
+    } else if r == 1 { // rule: lose
+        (t,if t == 1 {3} else if t == 2 {1} else {2})
+    } else {
+        (t,if t == 1 {2} else if t == 2 {3} else {1})
+    }
+}
+
+fn parse_hand(input: &str) -> (u32,u32) {
+    let (left, right) = input.split_at(1);
+    let mut numeric_hand : (u32,u32) = (0,0);
+    match left {
+    "A" => numeric_hand.0 = 1,
+    "B" => numeric_hand.0 = 2,
+    "C" => numeric_hand.0 = 3,
+    _ => panic!("fuckup!")
+    }
+    match right {
+    " X" => numeric_hand.1 = 1,
+    " Y" => numeric_hand.1 = 2,
+    " Z" => numeric_hand.1 = 3,
+    _ => panic!("fuckup!")
+    }
+    numeric_hand
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+
+    Some(input.lines().map(parse_hand).map(score_hand).sum())
+
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    Some(input.lines().map(parse_hand).map(play_hand).map(score_hand).sum())
+}
+
+fn main() {
+    let input = &advent_of_code::read_file("inputs", 2);
+    advent_of_code::solve!(1, part_one, input);
+    advent_of_code::solve!(2, part_two, input);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let input = advent_of_code::read_file("examples", 2);
+        assert_eq!(part_one(&input), Some(15));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let input = advent_of_code::read_file("examples", 2);
+        assert_eq!(part_two(&input), Some(12));
+    }
+}

src/examples/02.txt

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z