Day 7

07/part1.js

@@ -0,0 +1,76 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+
+let equations = [];
+const input = readFileSync(inputFile).toString();
+input.split("\n").forEach((line) => {
+  if (line.split(":").length > 1) {
+    equations.push({
+      target: parseInt(line.split(":")[0]),
+      numbers: line
+        .split(":")[1]
+        .trim()
+        .split(" ")
+        .map((x) => parseInt(x)),
+      operators: [],
+      isValid: false,
+    });
+  }
+});
+
+function evaluateEquation(equation) {
+  let result = equation.numbers[0];
+  equation.numbers.forEach((n, i) => {
+    if (i != 0) {
+      let operator = equation.operators[i - 1];
+      if (operator == "+") {
+        result += n;
+      } else {
+        result *= n;
+      }
+    }
+  });
+
+  equation.isValid = result == equation.target;
+}
+
+function convertPaternToOperators(pattern) {
+  return pattern
+    .toString(2)
+    .split("")
+    .slice(1)
+    .map((x) => (x == 1 ? "*" : "+"));
+}
+
+function bruteforceEquation(equation) {
+  let operatorsCount = equation.numbers.length - 1;
+  let currentPattern = 1 << operatorsCount;
+
+  let currentOffset = 0;
+  let maxOffset = 2 ** operatorsCount;
+
+  while (currentOffset <= maxOffset) {
+    if (!equation.isValid) {
+      currentPattern = (1 << operatorsCount) + currentOffset;
+      equation.operators = convertPaternToOperators(currentPattern);
+      evaluateEquation(equation);
+      if (equation.isValid) break;
+      else currentOffset++;
+    }
+  }
+
+  return equation;
+}
+
+let result = 0;
+
+equations.forEach((e) => {
+  let parsed = bruteforceEquation(e);
+
+  if (parsed.isValid) {
+    result += parsed.target;
+  }
+});
+
+console.log(result);

07/part2.js

@@ -0,0 +1,78 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+
+let equations = [];
+const input = readFileSync(inputFile).toString();
+input.split("\n").forEach((line) => {
+  if (line.split(":").length > 1) {
+    equations.push({
+      target: parseInt(line.split(":")[0]),
+      numbers: line
+        .split(":")[1]
+        .trim()
+        .split(" ")
+        .map((x) => parseInt(x)),
+      operators: [],
+      isValid: false,
+    });
+  }
+});
+
+function evaluateEquation(equation) {
+  let result = equation.numbers[0];
+  equation.numbers.forEach((n, i) => {
+    if (i != 0) {
+      let operator = equation.operators[i - 1];
+      if (operator == "+") {
+        result += n;
+      } else if (operator == "*") {
+        result *= n;
+      } else {
+        result = parseInt(`${result}${n}`);
+      }
+    }
+  });
+
+  equation.isValid = result == equation.target;
+}
+
+function bruteforceEquation(equation) {
+  let operatorsCount = equation.numbers.length - 1;
+  let operators = ["+", "*", "||"];
+
+  equation.operators = new Array(operatorsCount).fill("+");
+
+  while (true) {
+    evaluateEquation(equation);
+    if (equation.isValid) break;
+
+    for (let i = operatorsCount - 1; i >= 0; i--) {
+      let currentIndex = operators.indexOf(equation.operators[i]);
+      if (currentIndex < operators.length - 1) {
+        equation.operators[i] = operators[currentIndex + 1];
+        break;
+      } else {
+        equation.operators[i] = operators[0];
+        if (i === 0) return equation;
+      }
+    }
+  }
+
+  return equation;
+}
+
+let result = 0;
+
+equations.forEach((e, i) => {
+  let parsed = bruteforceEquation(e);
+  process.stdout.write(
+    `Parsed : ${i + 1}/${equations.length}. Current Result : ${result}\r`,
+  );
+
+  if (parsed.isValid) {
+    result += parsed.target;
+  }
+});
+
+console.log("\n", result);