uva 10763 - Foreign Exchange

水题一个，边输入边处理，总数是奇数输出NO，或者只要最后的计数乘以2等于总数就输出YES，否则NO。

AC代码：

#include<cstdio>
#include<ctype.h>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
#include<stack>
#include<cmath>
#include<queue>
#include<set>
#include<ctime>
using namespace std;
#define NMAX 1000
#define ll long long
int vis[NMAX][NMAX];
int flag1[500005],flag2[500005];
int main()
{
// freopen("input.txt","r",stdin);
// freopen("o1.txt","w",stdout);
int i,j,n;
while(~scanf("%d",&n)&&n)
{
int nct = 0;
for(i = 0; i < n; i++)
{
int t1,t2;
scanf("%d%d",&t1,&t2);
vis[t1][t2] = 1;
flag1[i] = t1;
flag2[i] = t2;
if(vis[t2][t1])
{
vis[t1][t2] = vis[t1][t2] = 0;
nct++;
}
}
if(n%2)
{
printf("NO\n");
continue;
}
if(nct*2 == n)
printf("YES\n");
else
printf("NO\n");
for(i = 0 ; i < n; i++)
if(vis[flag1[i]][flag2[i]]) vis[flag1[i]][flag2[i]] = 0;
}
return 0;
}