uva11995--水题（训练指南）
#include<cstdlib>#include<iostream>#include<cstdio>#include<cmath>#include<cstring>#include<algorithm>#include<set>#include<map>#include<list>#include<stack>#include<queue>#include<vector>#define LL long long#define inf 0x7fffffff#define exp 1e-9#define M 100#define N 105using namespace std;int m,n,t;int main(){#ifndef ONLINE_JUDGE freopen("ex.in","r",stdin);#endif while(scanf("%d",&n)==1) { int qa=1,pqa=1,sa=1; queue<int> q; priority_queue<int> pq; stack<int> s; for (int i=0; i<n; ++i ) { int x; scanf("%d",&x); if(x==1) { scanf("%d",&x); q.push(x); pq.push(x); s.push(x); } else { scanf("%d",&x); int t; if(q.empty()) { qa=pqa=sa=0; continue;//wa } t=q.front(); q.pop(); if(t!=x) qa=0; t=pq.top(); pq.pop(); if(t!=x) pqa=0; t=s.top(); s.pop(); if(t!=x) sa=0; } } int ans=qa+pqa+sa; if(ans>=2) printf("not sure\n"); else if(ans==0) printf("impossible\n"); else if(qa) printf("queue\n"); else if(pqa) printf("priority queue\n"); else printf("stack\n"); } return 0;}