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 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 原题链接：https://www.patest.cn/contests/pat-a-practise/1051
https://www.nowcoder.com/pat/5/problem/4090
思路：
模拟
模拟栈的工作
CODE：
#include<iostream> #include<stack> using namespace std; int main() { int l,m,n; cin>>l>>m>>n; for (int i=0;i<n;i++) { stack<int> st; int tp=0; int fl=0; int too=0; for (int j=0;j<m;j++) { int t; cin>>t; if (fl==1) continue; if (t>tp && t-tp+st.size()>l) { //cout<<t<<" "<<tp<<" "<<st.size()<<" "<<t-tp+st.size()<<endl; fl=1; continue; } if (t<too) { //cout<<t<<" "<<tp<<endl; fl=1; continue; } for (int k=tp+1;k<=t;k++) st.push(k); tp=max(tp,st.top()); st.pop(); if (st.empty()) too=0; else too=st.top(); //cout<<tp<<" "<<too<<endl; } if (fl==1) cout<<"NO"<<endl; else cout<<"YES"<<endl; } return 0; }
