Implement solutions for Day 13

Author: slgeay

data/examples/13.txt

@@ -0,0 +1,15 @@
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279

src/bin/13.rs

@@ -0,0 +1,32 @@
+use regex::Regex;
+
+advent_of_code::solution!(13);
+
+#[rustfmt::skip]
+pub fn part_one(input: &str) -> Option<u64> {
+    Some(input.split("\n\n").map(|machine|{Regex::new(r"(?s)(\d+).+\+(\d+).+\+(\d+).+\+(\d+).+=(\d+).+=(\d+)").unwrap().captures(machine).unwrap().iter().skip(1).map(|n|n.unwrap().as_str().parse::<f64>().unwrap()).collect::<Vec<_>>()}).map(|m|{let b=(m[5]*m[0]-m[4]*m[1])/(m[0]*m[3]-m[2]*m[1]);if b.fract()==0.0{let a=(m[4]-b*m[2])/m[0];return if a.fract()==0.0{(3.0*a+b)as u64}else{0}}0}).sum())
+}
+
+const D: f64 = 10000000000000.0;
+
+#[rustfmt::skip]
+pub fn part_two(input: &str) -> Option<u64> {
+    Some(input.split("\n\n").map(|machine|{Regex::new(r"(?s)(\d+).+\+(\d+).+\+(\d+).+\+(\d+).+=(\d+).+=(\d+)").unwrap().captures(machine).unwrap().iter().skip(1).map(|n|n.unwrap().as_str().parse::<f64>().unwrap()).collect::<Vec<_>>()}).map(|m|{let b=((D+m[5])*m[0]-(D+m[4])*m[1])/(m[0]*m[3]-m[2]*m[1]);if b.fract()==0.0{let a=((D+m[4])-b*m[2])/m[0];return if a.fract()==0.0{(3.0*a+b)as u64}else{0}}0}).sum())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(480));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(875318608908));
+    }
+}