sicily 1021 Couples

刚开始一直超时，还是没有完全掌握灵活运用数据结构。

才发现用STL这么方便！！！

 

#include <iostream>
#include <stack>
using namespace std;

int main() {
    int n;
    while (cin>>n,n!=0) {
        int m[2*n+1];
        for (int i = 0; i <= 2*n; i++) m[i] = 0;
        for (int i = 1; i <= n; i++) {
            int a, b;
            cin>>a>>b;
            m[a] = m[b] = i;
        }
        stack<int> s;
        for (int i = 1; i <= 2*n; i++) {
            if (s.empty()||s.top()!=(m[i]+'0')) s.push(m[i]+'0');
            else if (!s.empty()||s.top()==(m[i]+'0')) s.pop();
        }
        if (s.empty()) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
    return 0;
}