import java.util.ArrayList; import java.util.*; public class Solution { public boolean IsPopOrder(int [] pushA,int [] popA) { if(pushA.length==0||popA.length==0){ return false; } Stack<Integer> s =new Stack<>(); int j=0; for(int i=0;i<pushA.length;i++){ s.push(pushA[i]); while(!s.empty()&&s.peek()==popA[j]){ s.pop(); j++; } } return s.empty(); } }