[ts] 2024:07: Solve part 1

Author: kiriDevs

2024/day07/day07.ts

@@ -0,0 +1,59 @@
+// @ts-ignore - tl_ls is missing @types/node
+import { EOL } from "node:os";
+// @ts-ignore - tl_ls doesn't know about Bun
+const inputLines = (await Bun.file("input").text()).trim().split(EOL);
+
+type Equation = { total: number, values: Array<number> };
+const OPERATORS = ["+", "*"] as const;
+type Operator = (typeof OPERATORS)[number];
+
+function testSolution(equation: Equation, operators: Array<Operator>) {
+    let computedSolution = equation.values[0];
+    for (let inx = 0; inx < equation.values.length; inx++) {
+        const value = equation.values[inx + 1];
+        switch (operators[inx]) {
+            case "+": computedSolution += value; break;
+            case "*": computedSolution *= value; break;
+        }
+    }
+    return computedSolution === equation.total;
+}
+
+function generateCandidates(equation: Equation, prev: Array<Operator>): Array<Array<Operator>> {
+    if (prev.length == (equation.values.length - 1)) return [prev];
+    const candidates: Array<Array<Operator>> = [];
+    for (let operator of OPERATORS) {
+        const extension = [...prev, operator];
+        const newCandidates = generateCandidates(equation, extension);
+        candidates.push(...newCandidates);
+    }
+    return candidates;
+}
+
+function isPossibleEquation(equation: Equation): boolean {
+    const operatorCandidates: Array<Array<Operator>> = generateCandidates(equation, []);
+
+    for (let operatorCandidate of operatorCandidates) {
+        if (testSolution(equation, operatorCandidate)) return true;
+    }
+    
+    return false;
+}
+
+const equations: Array<Equation> = inputLines.map((line: string) => {
+    const [totalString, valuesString] = line.split(/:\s+/);
+    const total = parseInt(totalString);
+    const values = valuesString.split(/\s+/).map((valueString) => parseInt(valueString));
+
+    return { total, values } as Equation;
+});
+
+const solution1 = equations
+    .filter(isPossibleEquation)
+    .map((equation) => equation.total)
+    .reduce((acc, total) => acc + total, 0);
+
+const solution2 = -1;
+
+console.log("Part 1:", solution1);
+console.log("Part 2:", solution2);