ACM寒假集训2019.1.23

题目链接：https://vjudge.net/contest/279629#problem
代码：

#include <iostream>
using namespace std;
int main()
{
	int n,sum=0;
	cin >> n;
	if (n < 2 || n>30)
		return 0;
	int *h = new int[n];
	int *a = new int[n];
	for (int i = 0; i < n; i++)
	{
		cin >> h[i] >> a[i];
		if (h[i] < 1 || h[i]>100 ||h[i]==a[i]|| a[i] < 1 || a[i]>100)
			return 0;
	}
	for (int i = 0; i < n; i++)
		for (int j = 0; j < n; j++)
			if (h[i] == a[j])
				sum++;
	cout << sum;
}