UVA 11995 I Can Guess the Data Structure! （STL的基本操作）

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).
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
Sample Output
queue
not sure
impossible
stack
priority queue

思路：模拟三种不同数据结构类型的基本操作就好，别想其它方法了宝贝们（我不会告诉你我没用STL之前WA了N次）

#include <iostream>#include <algorithm>#include <cstdio>#include <cstring>#include <sstream>#include <cmath>#include <map>#include <queue>#include <stack>using namespace std;const int maxn = 1e3 + 10;int n;int main(){    while(scanf("%d", &n)!=EOF)    {        if(n<1 || n>1000)            break;        queue<int> q1;        stack<int> s;        priority_queue<int> q2;        int flag1 = 1, flag2 = 1, flag3 = 1, x;        for(int i = 0; i < n; i++)        {            cin >> x;            if(x==1)            {               cin >> x;               q1.push(x);               q2.push(x);               s.push(x);            }            else            {                cin >> x;                if(s.empty())                {                    flag1 = flag2 = flag3 = 0;                    break;                }                int temp = s.top();                s.pop();                if(x!=temp)                    flag2 = 0;                temp = q1.front();                q1.pop();                if(x!=temp)                    flag1 = 0;                temp = q2.top();                q2.pop();                if(x!=temp)                    flag3 = 0;            //cout << flag1 << endl;            //cout << flag2 << endl;            //cout << flag3 << endl;            }        }        if(flag1+flag2+flag3>1)            cout << "not sure" << endl;        else if(flag3)            cout << "priority queue" << endl;        else if(flag1)            cout << "queue" << endl;        else if(flag2)            cout << "stack" << endl;        else            cout << "impossible" << endl;    }    return 0;}