uva 11995 I Can Guess the Data Structure!
题目很简单,就是不知道为啥总是runtime error;
后来发现我是先判断的y!=p.front();
应该先判断是否为空;
哎!今天果然不宜A题啊!
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include<queue> 2 #include<stack> 3 #include<cstdio> 4 using namespace std; 5 priority_queue<int>pq; 6 queue<int>q; 7 stack<int>s; 8 bool flag[4]; 9 int main() 10 { 11 int n,x,y; 12 while(scanf("%d",&n)!=EOF) 13 { 14 while(!q.empty())q.pop(); 15 while(!pq.empty())pq.pop(); 16 while(!s.empty())s.pop(); 17 flag[0]=1,flag[1]=1,flag[2]=1; 18 while(n--) 19 { 20 scanf("%d%d",&x,&y); 21 if(x==1) 22 { 23 pq.push(y); 24 q.push(y); 25 s.push(y); 26 } 27 else if(x==2) 28 { 29 if(flag[0]==1){if(pq.empty()||y!=pq.top())flag[0]=0; 30 else pq.pop();} 31 if(flag[1]==1){if(q.empty()||y!=q.front())flag[1]=0; 32 else q.pop();} 33 if(flag[2]==1){if(s.empty()||y!=s.top())flag[2]=0; 34 else s.pop();} 35 } 36 } 37 int cnt=0,ans=0; 38 for(int i=0; i<3; i++) 39 { 40 if(flag[i]==1) 41 { 42 cnt++; 43 ans+=i; 44 } 45 } 46 if(cnt==0)puts("impossible"); 47 else if(cnt>=2)puts("not sure"); 48 else 49 { 50 if(ans==0)puts("priority queue"); 51 else if(ans==1)puts("queue"); 52 else puts("stack"); 53 } 54 } 55 return 0; 56 }