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 using namespace std; 4 int M, N, K; 5 int main() 6 { 7 cin >> M >> N >> K; 8 for (int i = 0; i < K; ++i) 9 { 10 stack<int>s; 11 int a, b = 1, flag = 1; 12 for (int j = 0; j < N; ++j) 13 { 14 cin >> a; 15 while (s.size() < M && (s.empty() || s.top() != a)) 16 s.push(b++); 17 if (s.top() == a) 18 s.pop(); 19 else 20 flag = 0; 21 } 22 if (flag == 1) 23 cout << "Yes" << endl; 24 else 25 cout << "No" << endl; 26 } 27 return 0; 28 }