java代码

class Solution {
    public boolean isPopOrder(int [] pushV,int [] popV) {
        int pul = pushV.length;
        int pol = popV.length; 
        if(pul != pol) return false;
        if(pul == 0 && pol == 0) return true; 
        Stack stack = new Stack();
        int k = 0;
        int flag = 0;
        while(k < pul){
            if(pushV[k] == popV[flag]){
                k++;
                flag++;
            }else{
                if(stack.isEmpty() || !stack.peek().equals(popV[flag])){
                    stack.push(pushV[k]);
                    k++;
                }else{
                    stack.pop();
                    flag++;
                }
            }

        }
        if(stack.isEmpty()){
            return true;
        }
        // for(int i=flag;i<pol;i++){
        //     // System.out.print(popV[i]);
        //     System.out.print(stack.pop());
        // }
        while(flag < pol){
            if(!stack.pop().equals(popV[flag])){
                return false;
            }
            flag++;
        }
        return true;
    }
}