线性结构4 Pop Sequence

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, ..., Nand 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

#include<iostream>
#include<stack>
#include<vector>
#include<algorithm>
using namespace std;
int M,N,K;
int check(vector<int> &vi){
    int m=0,n=0,cap=M+1;
    stack<int> sta;
    sta.push(0); 
    while(n<N){
        while(sta.size()<cap&&vi[n]>sta.top())
            sta.push(++m);
        if(sta.top()==vi[n++]) sta.pop();
            else return 0;
        }    
    return 1;
}
int main()
{
    cin>>M>>N>>K;
    vector<int> vi(N,0);
    for(int j=0;j<K;j++){
        for(int i=0;i<N;i++){
        int n;
        cin>>n;
        vi[i]=n;}
        if(check(vi)) 
        cout<<"YES"<<endl;
        else 
        cout<<"NO"<<endl;
        vi.clear();    
    }
    return 0;    
 }