Solve day 13 (more pain)

input/13-0.in

@@ -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 +1,79 @@
+#![feature(iter_array_chunks)]
+use itertools::Itertools;
+use regex::Regex;
+
+fn main() {
+    let text = std::fs::read_to_string("input/13-1.in").unwrap();
+
+    let button_regex = Regex::new(r"^Button [AB]: X\+(\d+), Y\+(\d+)$").unwrap();
+
+    let prize_regex = Regex::new(r"^Prize: X=(\d+), Y=(\d+)$").unwrap();
+
+    let t = text
+        .lines()
+        .chain([""])
+        .array_chunks::<4>()
+        .map(|[a, b, c, _]| {
+            let ra = button_regex.captures(a).unwrap();
+            let ax = ra[1].parse::<u64>().unwrap();
+            let ay = ra[2].parse::<u64>().unwrap();
+            let rb = button_regex.captures(b).unwrap();
+            let bx = rb[1].parse::<u64>().unwrap();
+            let by = rb[2].parse::<u64>().unwrap();
+
+            let rp = prize_regex.captures(c).unwrap();
+            let px = rp[1].parse::<u64>().unwrap();
+            let py = rp[2].parse::<u64>().unwrap();
+
+            let amax = u64::max(px.div_ceil(ax), py.div_ceil(ay));
+            let bmax = u64::max(px.div_ceil(bx), py.div_ceil(by));
+            (0..amax)
+                .cartesian_product(0..bmax)
+                .filter(|(a, b)| (a * ax + b * bx == px) && (a * ay + b * by == py))
+                .map(|(a, b)| 3 * a + b)
+                .min()
+                .unwrap_or(0)
+        })
+        .sum::<u64>();
+
+    println!("{t}");
+
+    let t = text
+        .lines()
+        .chain([""])
+        .array_chunks::<4>()
+        .filter_map(|[a, b, c, _]| {
+            let ra = button_regex.captures(a).unwrap();
+            let ax = ra[1].parse::<i64>().unwrap();
+            let ay = ra[2].parse::<i64>().unwrap();
+            let rb = button_regex.captures(b).unwrap();
+            let bx = rb[1].parse::<i64>().unwrap();
+            let by = rb[2].parse::<i64>().unwrap();
+
+            let rp = prize_regex.captures(c).unwrap();
+            let offset = 10000000000000;
+            let px = rp[1].parse::<i64>().unwrap() + offset;
+            let py = rp[2].parse::<i64>().unwrap() + offset;
+
+            // dbg!(ax, ay, bx, by, px, py);
+
+            let upper_b = (py * ax) - (ay * px);
+            let lower_b = (by * ax) - (ay * bx);
+
+            if upper_b % lower_b == 0 {
+                let b = upper_b / lower_b;
+                if (px - bx * b) % ax == 0 {
+                    let a = (px - bx * b) / ax;
+                    // dbg!(a, b);
+                    Some(a * 3 + b)
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        })
+        .sum::<i64>();
+
+    println!("{t}");
+}