PAT 1051. Pop Sequence (25)

1051. Pop Sequence (25)

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 5
1 2 3 4 5 6 7
3 2 1 7 5 6 4
7 6 5 4 3 2 1
5 6 4 3 7 2 1
1 7 6 5 4 3 2

Sample Output:

YES
NO
NO
YES
NO

#include <iostream>
#include <stack>

using namespace std;

int sequence[1001];

int main()
{
    int maxCapacity, seqLength, queryNum;
    cin >> maxCapacity >> seqLength >> queryNum;

    for (int i = 0; i < queryNum; i++)
    {
        stack<int> Stack;
        for (int j = 0; j < seqLength; j++)
            cin >> sequence[j];
        int start = 1;
        int j = 0;
        while (j < seqLength)
        {
            while (start <= sequence[j])
            {
                Stack.push(start);
                start++;
                if (Stack.size() == maxCapacity)
                    break;
            }
            if (Stack.top() != sequence[j])
                break;
            Stack.pop();
            j++;
        }
        if (j == seqLength)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
}