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

最新推荐文章于 2018-05-13 03:52:18 发布

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最新推荐文章于 2018-05-13 03:52:18 发布

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分类专栏： # 数据结构文章标签： uva 模拟数据结构基础

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本文介绍了一种判断给定操作序列对应的数据结构类型的方法，包括栈、队列和优先队列等，并提供了一个C++实现示例。

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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.

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：

<span style="font-size:18px;">#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<functional>
using namespace std;
stack<int>sta;
queue<int>que;
priority_queue<int,vector<int>,less<int> >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"<<endl;
        else if(res>=2)cout<<"not sure"<<endl;
        else if(cun[1])cout<<"stack"<<endl;
        else if(cun[2])cout<<"queue"<<endl;
        else cout<<"priority queue"<<endl;
    }
    return 0;
}
</span>

多做水题有益身心健康~~~~~