Solve 2024 day 7 part 1

2024/day-07/main.cpp

@@ -0,0 +1,75 @@
+#include <cmath>
+#include <iostream>
+#include <sstream>
+#include <vector>
+
+using namespace std;
+
+struct Equation
+{
+    long result;
+    vector<int> numbers;
+};
+
+void readInput(vector<Equation> &equations)
+{
+    string line;
+    while (getline(cin, line)) {
+        stringstream stream(line);
+        Equation equation;
+
+        string result;
+        getline(stream, result, ':');
+        equation.result = stol(result);
+
+        int number;
+        while (stream >> number) {
+            equation.numbers.push_back(number);
+        }
+
+        equations.push_back(equation);
+    }
+}
+
+long computeEquationResult(const vector<int> &numbers, const size_t operatorMask)
+{
+    long testResult = numbers[0];
+
+    for (size_t numberIndex = 1; numberIndex < numbers.size(); numberIndex++) {
+        if (operatorMask & (1 << (numberIndex - 1))) {
+            testResult += numbers[numberIndex];
+        } else {
+            testResult *= numbers[numberIndex];
+        }
+    }
+
+    return testResult;
+}
+
+bool isValidEquation(const Equation &equation)
+{
+    const int operatorCount = equation.numbers.size() - 1;
+    const size_t operatorMaskLimit = pow(2, operatorCount) - 1;
+
+    for (size_t operatorMask = 0; operatorMask <= operatorMaskLimit; operatorMask++) {
+        if (computeEquationResult(equation.numbers, operatorMask) == equation.result) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+int main()
+{
+    vector<Equation> equations;
+    readInput(equations);
+
+    long totalCalibrationResult = 0;
+    for (const Equation &equation : equations) {
+        totalCalibrationResult += equation.result * isValidEquation(equation);
+    }
+
+    // Part one
+    cout << "Total Calibration Result: " << totalCalibrationResult << endl;
+}