class Solution {
    public boolean isPopOrder(int [] pushV,int [] popV) {
        Stack<Integer> stack = new Stack<>();
        if(pushV.length != popV.length) return false;
        int pushIndex = 0, popIndex = 0;
        while(pushIndex < pushV.length) {
            stack.push(pushV[pushIndex++]);
            while(!stack.isEmpty() && stack.peek() == popV[popIndex]){
                stack.pop();
                ++popIndex;
            }
        }
        return stack.isEmpty() && popIndex == popV.length;
    }
}