pat-a1051. Pop Sequence (25)

#include<cstdio>#include<stack>using namespace std;int num[1010];int a[1010];int main(){  int n,m,k;  scanf("%d%d%d",&n,&m,&k);  for(int i=0;i<=m;++i) a[i]=i+1;  for(int i=0;i<k;++i){    stack<int> ss;    for(int j=0;j<m;++j) scanf("%d",num+j);    int p=0,ok=1;    for(int j=0;j<m;++j){      if(a[j]!=num[p]){        ss.push(a[j]);        if(ss.size()>=n){          ok=0;          break;        }      }      else{        p++;        while(!ss.empty())         if(ss.top()==num[p]){           ss.pop();           p++;         }         else break;      }    }    if(!ss.empty()) ok=0;    if(ok) printf("YES\n");    else printf("NO\n");  }  return 0;}

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