Day 6 & 7

2024/07/index.ts

@@ -0,0 +1,34 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const equations: Array<string> = input.split("\n");
+
+let sum = 0;
+
+const operators = [(a: number, b: number) => a * b, (a: number, b: number) => a + b, /** Part 2 */ (a: number, b: number) => parseInt(''+a+b)];
+
+function recurseSum(carry: number, remaining: Array<number>, target: number, sum: string = ''): boolean {
+    if (!remaining.length) {
+        return target === carry;
+    }
+    const nextNum = remaining[0];
+    for (let o of operators) {
+        const newResult = recurseSum(o(carry, nextNum), remaining.slice(1), target);
+        if (newResult) {
+            return newResult;
+        }
+    };
+    return false;
+}
+
+equations.forEach((eq) => {
+    const [testStr, numStr] = eq.split(':');
+    const test = parseInt(testStr);
+    const nums = numStr.trim().split(' ').map((n) => parseInt(n));
+    if (recurseSum(nums[0], nums.slice(1), test)) {
+        sum += test;
+    }
+});
+
+console.log(sum);