不用排序一次遍历找数组中第二小的数

#include <iostream>
#include <vector>

using namespace std;

int main()
{	
	vector<int> a(100);
	for (int i = 99; i >= 0; --i) {
		a[i] = i - 50;
	}
	int firstmin;
	int	secondmin;
	if (a[0] < a[1]) {
		firstmin = a[0];
		secondmin = a[1];
	}
	else {
		secondmin = a[1];
		firstmin = a[0];
	}
	for (int i = 2; i < 100; i++) {
		if (a[i] < firstmin) {
			secondmin = firstmin;
			firstmin = a[i];
		}
		else if (a[i] > firstmin && a[i] < secondmin) {
			secondmin = a[i];
		}
	}
	cout << firstmin << " " << secondmin;
	return 0;
}