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
实现代码:
#include<iostream> #include<stack> #include<queue> using namespace std; int n, m, k; bool judge(queue<int> q) { stack<int> s; int i = 1; while (q.size()) { s.push(i); if (s.size() > m) return false; while (s.size()&&s.top() == q.front()) { s.pop(); q.pop(); } i++; } return true; } int main(void) { cin >> m >> n >> k; for (int i = 0; i < k; i++) { int data; queue<int> q; for (int j = 0; j < n; j++) { cin >> data; q.push(data); } if (judge(q)) cout << "YES"; else cout << "NO"; cout << endl; } }