add: try solving with lp

Cargo.lock

@@ -6,6 +6,7 @@ version = 3
 name = "advent-of-code-2024"
 version = "0.1.0"
 dependencies = [
+ "good_lp",
  "regex",
  "threadpool",
 ]
@@ -19,18 +20,93 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "bitflags"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4f67931368edf3a9a51d29886d245f1c3db2f1ef0dcc9e35ff70341b78c10d23"
+
+[[package]]
+name = "coin_cbc"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d602045cd2e7ad02608a71492af94357f493a6f3c934ce854c03bf10fddc5780"
+dependencies = [
+ "coin_cbc_sys",
+ "lazy_static",
+]
+
+[[package]]
+name = "coin_cbc_sys"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "085619f8bdc38e24e25c6336ecc3f2e6c0543d67566dff6daef0e32f7ac20f76"
+dependencies = [
+ "pkg-config",
+]
+
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
+[[package]]
+name = "gcc"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f5f3913fa0bfe7ee1fd8248b6b9f42a5af4b9d65ec2dd2c3c26132b950ecfc2"
+
+[[package]]
+name = "good_lp"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97630e1e456d7081c524488a87d8f8f7ed0fd3100ba10c55e3cfa7add5ce05c6"
+dependencies = [
+ "coin_cbc",
+ "fnv",
+ "lpsolve",
+]
+
 [[package]]
 name = "hermit-abi"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.167"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09d6582e104315a817dff97f75133544b2e094ee22447d2acf4a74e189ba06fc"
 
+[[package]]
+name = "lpsolve"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "516c671a8790d7b5a5c1f2140c36d3619335366fda108db1ca6d8359bd096ecd"
+dependencies = [
+ "bitflags",
+ "libc",
+ "lpsolve-sys",
+]
+
+[[package]]
+name = "lpsolve-sys"
+version = "5.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0776862d06b54bdea2ed14227f56a2913b39903e06849dce7b805d609ef6a85d"
+dependencies = [
+ "gcc",
+ "libc",
+]
+
 [[package]]
 name = "memchr"
 version = "2.7.4"
@@ -47,6 +123,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "pkg-config"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "953ec861398dccce10c670dfeaf3ec4911ca479e9c02154b3a215178c5f566f2"
+
 [[package]]
 name = "regex"
 version = "1.11.1"

Cargo.toml

@@ -4,5 +4,6 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+good_lp = {version = "1.10.0", features = ["lpsolve"]}
 regex = "1.11.1"
 threadpool = "1.8.1"

flake.nix

@@ -14,7 +14,7 @@
       {
         defaultPackage = naersk-lib.buildPackage ./.;
         devShell = with pkgs; mkShell {
-          buildInputs = [ cargo rustc rustfmt pre-commit rustPackages.clippy zip bash ];
+          buildInputs = [ cargo rustc rustfmt pre-commit rustPackages.clippy zip bash cbc lp_solve ];
           RUST_SRC_PATH = rustPlatform.rustLibSrc;
         };
       }

src/bin/d13p1.rs

@@ -0,0 +1,89 @@
+use std::collections::{HashMap, HashSet};
+
+use advent_of_code_2024::{make_main, next, Pair, SResult};
+use good_lp::{
+    coin_cbc, constraint::{self, eq}, variable, variables, Constraint, Expression, ProblemVariables,
+    Solution, SolverModel, WithMipGap,
+};
+use regex::Regex;
+
+make_main!();
+
+fn solve(lines: Vec<String>) -> SResult<(usize, usize)> {
+    let mut total = 0;
+    let mut total2 = 0;
+    let button_regex =
+        Regex::new(r"^Button (?<name>[^:]+): X\+(?<xvel>\d+), Y\+(?<yvel>\d+)$").unwrap();
+    let prize_regex = Regex::new(r"^Prize: X=(?<xpos>\d+), Y=(?<ypos>\d+)$").unwrap();
+    let mut buttons: HashMap<String, Pair> = HashMap::default();
+    for line in lines {
+        if line.trim() == "" {
+            buttons.clear();
+            continue;
+        }
+
+        if let Some(caps) = button_regex.captures(&line) {
+            let xvel = caps["xvel"].parse::<usize>().unwrap();
+            let yvel = caps["yvel"].parse::<usize>().unwrap();
+            buttons.insert(caps["name"].into(), (xvel, yvel));
+        } else if let Some(caps) = prize_regex.captures(&line) {
+            let xpos = caps["xpos"].parse::<usize>().unwrap();
+            let ypos = caps["ypos"].parse::<usize>().unwrap();
+            total += solve2(&buttons, (xpos, ypos));
+            let ans2 = solve2(&buttons, (xpos + 10000000000000, ypos + 10000000000000));
+            if ans2 > 0 {
+                println!("Solved for pos {}, {}", xpos, ypos);
+            }
+            total2 += ans2;
+        }
+    }
+    Ok((total, total2))
+}
+
+fn solve2(buttons: &HashMap<String, Pair>, prize: Pair) -> usize {
+    let ax = buttons["A"].0 as f64;
+    let ay = buttons["A"].1 as f64;
+    let bx = buttons["B"].0 as f64;
+    let by = buttons["B"].1 as f64;
+    variables! {
+        vars2:
+                0 <= a (integer) ;
+                0 <= b (integer) ;
+    }
+
+    let sol = match vars2.minimise(a * 3 + b)
+        .using(coin_cbc)
+        .with(eq(a*ax+b*bx, prize.0 as f64))
+        .with(eq(a*ay+b*by, prize.1 as f64))
+        .solve() {
+        Ok(s) => s,
+        Err(_) => return 0,
+    };
+
+    println!("a {}", sol.value(a));
+    println!("b {}", sol.value(b));
+    let a = sol.value(a).round() as usize;
+    let b = sol.value(b).round() as usize;
+
+
+    let ax = buttons["A"].0;
+    let ay = buttons["A"].1;
+    let bx = buttons["B"].0;
+    let by = buttons["B"].1;
+    assert_eq!((a*ax + b*bx, a*ay+b*by), prize);
+
+    a * 3 + b
+}
+
+#[cfg(test)]
+mod tests {
+    use advent_of_code_2024::input;
+
+    use super::*;
+    #[test]
+    fn lp_solve() {
+        let strings: Vec<String> = input!("d13p1.txt");
+        let got = solve(strings).unwrap();
+        assert_eq!(got, (480, 0));
+    }
+}

src/bin/d13p1.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