【暑假】[实用数据结构]UVa11995 I Can Guess the Data Structure!

UVa11995  I Can Guess the Data Structure!

思路：边读边模拟，注意empty的判断！

代码如下：

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

int main(){
queue<int> q;
priority_queue<int> pri_q;
stack<int> sta;
int n;
  while(cin>>n){
     while(!q.empty()) q.pop();        //清空data
     while(!pri_q.empty()) pri_q.pop();
     while(!sta.empty()) sta.pop();

     int a,b,c; a=b=c=1;
     while(n--) {
         int op,x;
         cin>>op>>x;
         if(op == 1){
             if(a) q.push(x);
            if(b) pri_q.push(x);
            if(c) sta.push(x);
         }
         else {
             if(a) if(q.empty()) a=0; else {a= q.front()==x; q.pop();}
             if(b) if(pri_q.empty()) b=0; else{b= pri_q.top()==x; pri_q.pop();}
             if(c) if(sta.empty()) c=0; else{c= sta.top()==x; sta.pop();}
         }
     }
     if(!a && !b &&!c) cout<<"impossible";
     else
      if((a&&b) || (a&&c) ||(b&&c)) cout<<"not sure";
      else{
          if(a) cout<<"queue";
          else if(b) cout<<"priority queue";
          else cout<<"stack";
      }
     cout<<"\n";
  }
  return 0;
}