Solve day 3 part 1

day_3.cpp

@@ -0,0 +1,40 @@
+#include <fstream>
+#include <iostream>
+
+int main()
+{
+	std::ifstream file("input.txt");
+
+	int joltage_sum = 0;
+
+	std::string bank;
+	while (getline(file, bank)) {
+		int first_index;
+		for (int i = 9; i > 0; i--) {
+			char digit = i + 48;
+
+			first_index = bank.find(digit);
+
+			if (first_index != bank.size() - 1 && first_index != std::string::npos)
+				break;
+		}
+
+		int second_index;
+		for (int i = 9; i > 0; i--) {
+			char digit = i + 48;
+
+			second_index = bank.find(digit, first_index + 1);
+
+			if (second_index != std::string::npos)
+				break;
+		}
+
+		int joltage = std::stoi(std::string { bank[first_index], bank[second_index] });
+
+		std::cout << joltage << std::endl;
+
+		joltage_sum += joltage;
+	}
+
+	std::cout << "\nSum: " << joltage_sum << std::endl;
+}