1051. Pop Sequence

Given a stack which can keep M numbers at most. Push N numbers in the order of 1, 2, 3, ..., N and pop randomly. You are supposed to tell if a given sequence of numbers is a possible pop sequence of the stack. For example, if M is 5 and N is 7, we can obtain 1, 2, 3, 4, 5, 6, 7 from the stack, but not 3, 2, 1, 7, 5, 6, 4.

Input Specification:

Each input file contains one test case. For each case, the first line contains 3 numbers (all no more than 1000): M (the maximum capacity of the stack), N (the length of push sequence), and K (the number of pop sequences to be checked). Then K lines follow, each contains a pop sequence of N numbers. All the numbers in a line are separated by a space.

Output Specification:

For each pop sequence, print in one line "YES" if it is indeed a possible pop sequence of the stack, or "NO" if not.

Sample Input:

5 7 51 2 3 4 5 6 73 2 1 7 5 6 47 6 5 4 3 2 15 6 4 3 7 2 11 7 6 5 4 3 2

Sample Output:

YES
NO
NO
YES

NO

#include <cstdio>

#include <cstdlib>

#include <iostream>

#include <deque>

#include <queue>

#include <cstring>

#include <vector>

#include <string>

#include <iomanip>

#include <cmath>

#include <stack>

#include <algorithm>

using namespace std;

#define max1 10001

#define inf 6000

int M,N,K;

int main()

{

    cin>>M>>N>>K;

    int num;

    for(int i=0;i<K;i++)

    {

        bool flag=true;

        stack<int>s;

        int cur=1;

        for(int j=0;j<N;j++)

        {

            cin>>num;

            while(s.empty()||s.top()<num)

            {

                s.push(cur);

                if(s.size()>M)

                {

                    flag=false;

                    break;

                }

                cur++;

            }

            if(flag&&s.top()==num&&s.size()>=1)

                s.pop();

            else

                flag=false;

        }

        if(flag)

            cout<<"YES"<<endl;

        else

            cout<<"NO"<<endl;

    }

    return 0;

}