Problem I
I Can Guess the Data Structure!
There is a bag-like data structure, supporting two operations:
1 x
Throw an element x into the bag.
2
Take out an element from the bag.
Given a sequence of operations with return values, you‘re going to guess the data structure. It is a stack (Last-In, First-Out), a queue (First-In, First-Out), a priority-queue (Always take out larger elements first) or something else that you can hardly imagine!
Input
There are several test cases. Each test case begins with a line containing a single integer n (1<=n<=1000). Each of the next n lines is either a type-1 command, or an integer 2 followed by an integer x. That means after executing a type-2 command, we get an element x without error. The value of x is always a positive integer not larger than 100. The input is terminated by end-of-file (EOF). The size of input file does not exceed 1MB.
Output
For each test case, output one of the following:
stack
It‘s definitely a stack.
queue
It‘s definitely a queue.
priority queue
It‘s definitely a priority queue.
impossible
It can‘t be a stack, a queue or a priority queue.
not sure
It can be more than one of the three data structures mentioned above.
Sample Input
6 1 1 1 2 1 3 2 1 2 2 2 3 6 1 1 1 2 1 3 2 3 2 2 2 1 2 1 1 2 2 4 1 2 1 1 2 1 2 2 7 1 2 1 5 1 1 1 3 2 5 1 4 2 4
Output for the Sample Input
queue not sure impossible stack priority queue
题目大意:根据数据的操作<1>插入<2>删除判别是哪一种数据类型,有栈、队列、优先队列几种类型,如三种
都不符合输出impossbile,符合两种以上输出not sure,只符合一种的对应输出它的类型名称。
#include <iostream> #include <queue> #include <stack> #include <cstdio> #define Max 1010 using namespace std; int N; int op[Max],num[Max]; stack<int> S; queue<int> Q; priority_queue<int> PQ; int check_stack() { int i,t; while(!S.empty()) S.pop(); for(i=0;i<N;i++) { if(op[i]==2) { if(S.empty()) return 0; t=S.top();S.pop(); if(t!=num[i]) return 0; } else S.push(num[i]); } return 1; } int check_queue() { int i,t; while(!Q.empty()) Q.pop(); for(i=0;i<N;i++) { if(op[i]==2) { if(Q.empty()) return 0; t=Q.front();Q.pop(); if(t!=num[i]) return 0; } else Q.push(num[i]); } return 1; } int check_priorityqueue() { int i,t; while(!PQ.empty()) PQ.pop(); for(i=0;i<N;i++) { if(op[i]==2) { if(PQ.empty()) return 0; t=PQ.top();PQ.pop(); if(t!=num[i]) return 0; } else PQ.push(num[i]); } return 1; } int main() { int i; int s,q,pq; while(scanf("%d",&N)!=EOF) { for(i=0;i<N;i++) scanf("%d %d",op+i,num+i); s=check_stack(); q=check_queue(); pq=check_priorityqueue(); if(!s && !q && !pq) printf("impossible\n"); else if(s && !q && !pq) printf("stack\n"); else if(!s && q && !pq) printf("queue\n"); else if(!s && !q && pq) printf("priority queue\n"); else printf("not sure\n"); } return 0; }