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

 1 #include <iostream>
 2 #include <stack>
 3
 4 using namespace std;
 5
 6 int sequence[1001];
 7
 8 int main()
 9 {
10     int maxCapacity, seqLength, queryNum;
11     cin >> maxCapacity >> seqLength >> queryNum;
12
13     for (int i = 0; i < queryNum; i++)
14     {
15         stack<int> Stack;
16         for (int j = 0; j < seqLength; j++)
17             cin >> sequence[j];
18         int start = 1;
19         int j = 0;
20         while (j < seqLength)
21         {
22             while (start <= sequence[j])
23             {
24                 Stack.push(start);
25                 start++;
26                 if (Stack.size() == maxCapacity)
27                     break;
28             }
29             if (Stack.top() != sequence[j])
30                 break;
31             Stack.pop();
32             j++;
33         }
34         if (j == seqLength)
35             cout << "YES" << endl;
36         else
37             cout << "NO" << endl;
38     }
39 }