Day 13

13/part1.js

@@ -0,0 +1,52 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString().trim();
+const machines = [];
+
+input.split("\n\n").forEach((m) => {
+  const regex = /X[+=](\d+).*?Y[+=](\d+)/g;
+  let match;
+  const results = [];
+  while ((match = regex.exec(m.trim())) !== null) {
+    results.push({ X: parseInt(match[1]), Y: parseInt(match[2]) });
+  }
+
+  machines.push({
+    id: machines.length,
+    buttonA: [results[0].X, results[0].Y],
+    buttonB: [results[1].X, results[1].Y],
+    prize: [results[2].X, results[2].Y],
+    result: null,
+  });
+});
+
+function solveEquationSystem(machine) {
+  let a = machine.buttonA[0];
+  let b = machine.buttonB[0];
+  let c = machine.buttonA[1];
+  let d = machine.buttonB[1];
+  let m1 = machine.prize[0];
+  let m2 = machine.prize[1];
+
+  let y = (a * m2 - c * m1) / (-c * b + d * a);
+  let x = (m1 - b * y) / a;
+
+  if (
+    Number.isInteger(y) &&
+    y >= 0 &&
+    y <= 100 &&
+    Number.isInteger(x) &&
+    x >= 0 &&
+    x <= 100
+  )
+    machine.result = [x, y];
+}
+
+let result = 0;
+machines.forEach((m) => {
+  solveEquationSystem(m);
+  if (m.result) result += m.result[0] * 3 + m.result[1];
+});
+
+console.log(result);

13/part2.js

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+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString().trim();
+const machines = [];
+
+input.split("\n\n").forEach((m) => {
+  const regex = /X[+=](\d+).*?Y[+=](\d+)/g;
+  let match;
+  const results = [];
+  while ((match = regex.exec(m.trim())) !== null) {
+    results.push({ X: parseInt(match[1]), Y: parseInt(match[2]) });
+  }
+
+  machines.push({
+    id: machines.length,
+    buttonA: [results[0].X, results[0].Y],
+    buttonB: [results[1].X, results[1].Y],
+    prize: [results[2].X + 10000000000000, results[2].Y + 10000000000000],
+    result: null,
+  });
+});
+
+function solveEquationSystem(machine) {
+  let a = machine.buttonA[0];
+  let b = machine.buttonB[0];
+  let c = machine.buttonA[1];
+  let d = machine.buttonB[1];
+  let m1 = machine.prize[0];
+  let m2 = machine.prize[1];
+
+  let y = (a * m2 - c * m1) / (-c * b + d * a);
+  let x = (m1 - b * y) / a;
+
+  if (Number.isInteger(y) && y >= 0 && Number.isInteger(x) && x >= 0)
+    machine.result = [x, y];
+}
+
+let result = 0;
+machines.forEach((m) => {
+  solveEquationSystem(m);
+  if (m.result) result += m.result[0] * 3 + m.result[1];
+});
+
+console.log(result);