Solve 2024 day 3 part 1

2024/day-03/main.cpp

@@ -0,0 +1,93 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+vector<string> readInput()
+{
+    vector<string> lines;
+    string line;
+    while (getline(cin, line)) {
+        lines.push_back(line);
+    }
+    return lines;
+}
+
+bool isNumber(const string &potentialNumber)
+{
+    for (const char c : potentialNumber) {
+        if (!isdigit(c)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+string getNextValidInstruction(string &line)
+{
+    while (true) {
+        {
+            size_t startPosition = line.find("mul(");
+            if (startPosition == string::npos) {
+                return "";
+            }
+            line.erase(0, startPosition);
+        }
+
+        size_t commaPosition = line.find(',');
+        if (commaPosition == string::npos) {
+            return "";
+        }
+
+        size_t closingBracketPosition = line.find(')');
+        if (closingBracketPosition == string::npos) {
+            return "";
+        }
+
+        int lengthOfNumber1 = commaPosition - 4;
+        int lengthOfNumber2 = closingBracketPosition - commaPosition - 1;
+        if ((lengthOfNumber1 < 1 || lengthOfNumber1 > 3)
+            || (lengthOfNumber2 < 1 || lengthOfNumber2 > 3)) {
+            line.erase(0, 4);
+            continue;
+        }
+
+        if (!isNumber(line.substr(4, lengthOfNumber1))
+            || !isNumber(line.substr(commaPosition + 1, lengthOfNumber2))) {
+            line.erase(0, 4);
+            continue;
+        }
+
+        string validInstruction = line.substr(0, closingBracketPosition + 1);
+        line.erase(0, closingBracketPosition + 1);
+
+        return validInstruction;
+    }
+}
+
+int getInstructionResult(const string &instruction)
+{
+    size_t commaPosition = instruction.find(',');
+    int number1 = stoi(instruction.substr(4, commaPosition - 4));
+    int number2 = stoi(
+        instruction.substr(commaPosition + 1, instruction.length() - commaPosition - 1));
+    return number1 * number2;
+}
+
+int main()
+{
+    vector<string> lines = readInput();
+    int finalResult = 0;
+
+    for (string &line : lines) {
+        while (true) {
+            string instruction = getNextValidInstruction(line);
+            if (instruction == "") {
+                break;
+            }
+            finalResult += getInstructionResult(instruction);
+        }
+    }
+
+    cout << "Sum of all the multiplication: " << finalResult << endl;
+}