1051 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.
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.
For each pop sequence, print in one line "YES" if it is indeed a possible pop sequence of the stack, or "NO" if not.
#include <bits/stdc++.h> using namespace std; const int maxn=1001; int arr[maxn]; stack<int>st; int main() { int n,m,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 flas=true; for(int i=1; i<=n; i++) { st.push(i); if(st.size()>m) { flas=false; break; } while(!st.empty()&&st.top()==arr[current]) { st.pop(); current++; } } if(st.empty()==true&&flas==true) { printf("YES\n"); } else { printf("NO\n"); } } return 0; }
