UVa 10763 Foreign Exchange

#include<iostream>#include<cstdio>#include<string>#include<map>#include<sstream>#include<algorithm>#include<vector>#include<queue>#include<set>#include<cstring>#include<stack>#include<iomanip>#include<math.h>using namespace std;int main(){int n;while(scanf("%d",&n)!=EOF&&n!=0){int i,j;pair<int,int> temp;map<pair<int,int>,int> pair2int;vector<pair<int,int> > v;for(i=0;i<n;i++){int a,b;scanf("%d %d",&a,&b);temp.first=a;temp.second=b;if(pair2int.count(temp)==0){pair2int[temp]=1;v.push_back(temp);}elsepair2int[temp]++;}bool istr=true;for(i=0;i<v.size();i++){pair<int,int> temp2;temp2.first=v[i].second;temp2.second=v[i].first;if(pair2int[temp2]!=pair2int[v[i]]){istr=false;break;}}if(istr){printf("YES\n");}else{printf("NO\n");}}return 0;}