MOOC 数据结构 Pop Sequence

MOOC 数据结构 Pop Sequence

原题地址

题目描述

Given a stack which can keep MM numbers at most. Push NN numbers in the order of 1, 2, 3, ..., NN 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 MM is 5 and NN 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): MM (the maximum capacity of the stack), NN (the length of push sequence), and KK (the number of pop sequences to be checked). Then KK lines follow, each contains a pop sequence of NN 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 2Sample Output:YESNONOYESNO

代码实现

#include<iostream>#include<cstdio>#include<stack>using namespace std;int main(){   stack<int> s;   int M,N,K;   cin>>M>>N>>K;   for(int i=0;i<K;i++){     int tmp=1;     bool flag=1;     for(int j=0;j<N;j++){        int input;        cin>>input;        while(s.size()<=M && flag){           if(s.empty() || s.top()!=input){              s.push(tmp++);           }           else if(s.top()==input){               s.pop();               break;           }           if(s.size()>M){             flag=0;             break;           }        }      }     if(flag)        cout<<"YES"<<endl;     else        cout<<"NO"<<endl;     while(!s.empty()){        s.pop();     }   }   return 0;}