Solve 2024-07

2024/07/index.ts

@@ -0,0 +1,59 @@
+import { sumBy } from '../../utils/array.ts';
+
+export function solveFirst(input: string): number {
+  const regex = /^(\d*): (.*)$/gm;
+  const match = input.matchAll(regex);
+
+  const rows = Array.from(match, (m) => ({
+    sum: Number(m[1]),
+    digits: m[2].split(' ').map((n) => Number(n))
+  }));
+
+  const possible = rows.filter((r) => {
+    for (let t = 0; t < Math.pow(2, r.digits.length - 1); t++) {
+      const sol = r.digits.reduce((sum, curr, i) =>
+        evalTry(t, i, sum + curr, sum * curr)
+      );
+      if (sol === r.sum) {
+        return true;
+      }
+    }
+    return false;
+  });
+
+  // console.log(possible);
+  return sumBy(possible, (p) => p.sum);
+}
+
+export function evalTry<T>(t: number, index: number, ...choices: T[]): T {
+  const base = choices.length;
+  const choice = Math.max(0, Math.floor(t / Math.pow(base, index - 1)) % base);
+
+  return choices[choice];
+}
+
+export function solveSecond(input: string): number {
+  const regex = /^(\d*): (.*)$/gm;
+  const match = input.matchAll(regex);
+
+  const rows = Array.from(match, (m) => ({
+    sum: Number(m[1]),
+    digits: m[2].split(' ').map((n) => Number(n))
+  }));
+
+  const possible = rows.filter((r) => {
+    for (let t = 0; t < Math.pow(3, r.digits.length - 1); t++) {
+      const sol = r.digits.reduce((sum, curr, i) =>
+        evalTry(t, i, sum * curr, sum + curr, Number(`${sum}${curr}`))
+      );
+      if (sol === r.sum) {
+        return true;
+      }
+    }
+
+    return false;
+  });
+
+  // console.log(possible);
+  return sumBy(possible, (p) => p.sum);
+}