edited performance printout

I don't want to hardcode the number of lines in the input file.

days/day01.cpp

@@ -153,10 +153,13 @@ Once again consider your left and right lists. What is their similarity score?
 void day01::Part2()
 {
 	std::vector<int> col1;
-	std::vector<int> col2;
 	std::unordered_map<int, int> occurrence_map;
 	int sum = 0;
 
+	size_t estimated_size = 1000;
+	col1.reserve(estimated_size);
+	occurrence_map.reserve(estimated_size);
+
 	std::ifstream input("input/day01.txt");
 	//std::ifstream input("input/day01short.txt");
 
@@ -168,31 +171,17 @@ void day01::Part2()
 		return;
 	}
 
-	std::string delimiter = "   ";
-	auto delimiterLength = delimiter.length();
-
 	std::string line;
-	while (std::getline(input, line))
+	int num1, num2;
+	while (input >> num1 >> num2)
 	{
-		auto delimiterPos = line.find(delimiter);
+		col1.emplace_back(num1);
-		col1.emplace_back(std::stoi(line.substr(0, delimiterPos)));
+		occurrence_map[num2]++;
-		col2.emplace_back(std::stoi(line.substr(delimiterPos + delimiterLength, line.length())));
-	}
-
-	for (auto number: col2)
-	{
-		if (occurrence_map.contains(number))
-		{
-			occurrence_map[number]++;
-		} else
-		{
-			occurrence_map[number] = 1;
-		}
 	}
 
 	for (auto number: col1)
 	{
 		sum += number * occurrence_map[number];
 	}
-	printf("Sum of all occurrence pairs is: %d\n", sum);
+	//printf("Sum of all occurrence pairs is: %d\n", sum);
 }

main.cpp

@@ -5,9 +5,25 @@
 
 int main()
 {
-	const auto startTime = std::chrono::high_resolution_clock::now();
+	double lowest = 10000;
-	day01::Part2();
+	double totalTime = 0;
-	const auto endTime = std::chrono::high_resolution_clock::now();
+	constexpr int cycles = 10000;
-	const std::chrono::duration<double> diff = endTime - startTime;
+	for (int i = 1; i <= cycles; i++)
-	std::cout << "Execution time: " << diff.count() * 1e6 << " μs" << std::endl;
+	{
+		const auto startTime = std::chrono::high_resolution_clock::now();
+		day01::Part2();
+		const auto endTime = std::chrono::high_resolution_clock::now();
+		const std::chrono::duration<double> diff = endTime - startTime;
+
+		totalTime += diff.count();
+		if (diff.count() < lowest)
+		{
+			lowest = diff.count();
+		}
+	}
+	const double average = totalTime / cycles;
+	std::cout << "Ran " << cycles << " cycles. "
+			<< "Execution time avg: " << average * 1e6 << " μs. Lowest: "
+			<< lowest
+			* 1e6 << " μs" << std::endl;
 }