02-线性结构4 Pop Sequence (25分)

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

借鉴别人的代码

#include <cstdio>#include <stack>using namespace std;const int maxn = 1010;int arr[maxn];stack<int> st;int main() {    int m, n, T;    scanf("%d%d%d", &m, &n, &T);    while(T--) {        while(!st.empty()) {            st.pop();        }        for(int i = 1; i <= n; i++) {            scanf("%d", &arr[i]);        }        int current = 1;        bool flag = true;        for(int i = 1; i <= n; i++) {            st.push(i);            if(st.size() > m) {                flag = false;                break;            }            while(!st.empty() && st.top() == arr[current]) {                st.pop();                current++;            }        }        if(st.empty() == true && flag == true) {            printf("YES\n");        } else {            printf("NO\n");        }    }    return 0;}