UVA11995 I Can Guess the Data Structure!（数据结构，模拟）

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 xwithout 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

额，这是一道简单的模拟题，注意优先队列只需要考虑大的在前的情况就行了。。。。。

代码如下：

#include
#include
#include
#include
#include
#include
#include
using namespace std;
stacksta;
queueque;
priority_queue,less >pqu1;

bool cun[4];
int main()
{
    int n;
    int a,b;
    while(cin>>n)
    {
        memset(cun,true,sizeof(cun));
        while(!sta.empty())sta.pop();
        while(!que.empty())que.pop();
        while(!pqu1.empty())pqu1.pop();
        while(n--)
        {
            cin>>a>>b;
            if(a==1)
            {
                if(cun[1])sta.push(b);
                if(cun[2])que.push(b);
                if(cun[3])pqu1.push(b);
            }
            else
            {
                if(cun[1]&&!sta.empty()&&b==sta.top())
                    sta.pop();
                else cun[1]=false;
                if(cun[2]&&!que.empty()&&b==que.front())
                    que.pop();
                else cun[2]=false;
                if(cun[3]&&!pqu1.empty()&&b==pqu1.top())
                    pqu1.pop();
                else cun[3]=false;
            }
        }
        int res=0;
        for(int i=1; i<5; i++)
            if(cun[i])res++;
        if(res==0)cout<<"impossible"<=2)cout<<"not sure"<

多做水题有益身心健康~~~~~