PAT 甲级 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 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:

YESNONOYESNO

#include <iostream>#include <vector>#include <algorithm>#include <cstring>#include <stack>using namespace std;int main() {int m, n, k;scanf("%d %d %d", &m, &n, &k);for (int i = 0; i < k; i++) {bool flag = false;stack<int>s;vector<int> v(n + 1);for (int j = 1; j <= n; j++) {scanf("%d", &v[j]);}int current = 1;for (int j = 1; j <= n; j++) {s.push(j);if (s.size() > m) break;while (!s.empty() && s.top() == v[current]) {s.pop();current++;}}if (current == n + 1) flag = true;if (flag) printf("YES\n");else printf("NO\n");}return 0;}