'''
Description: 
Autor: Au3C2
Date: 2021-03-23 11:11:09
LastEditors: Au3C2
LastEditTime: 2021-03-23 11:11:45
'''
# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
#class NestedInteger:
#    def isInteger(self) -> bool:
#        """
#        @return True if this NestedInteger holds a single integer, rather than a nested list.
#        """
#
#    def getInteger(self) -> int:
#        """
#        @return the single integer that this NestedInteger holds, if it holds a single integer
#        Return None if this NestedInteger holds a nested list
#        """
#
#    def getList(self) -> [NestedInteger]:
#        """
#        @return the nested list that this NestedInteger holds, if it holds a nested list
#        Return None if this NestedInteger holds a single integer
#        """

class NestedIterator(object):

    def __init__(self, nestedList):
        self.stack = []
        for i in range(len(nestedList) - 1, -1, -1):
            self.stack.append(nestedList[i])
        

    def next(self):
        cur = self.stack.pop()
        return cur.getInteger()

    def hasNext(self):
        while self.stack:
            cur = self.stack[-1]
            if cur.isInteger():
                return True
            self.stack.pop()
            for i in range(len(cur.getList()) - 1, -1, -1):
                self.stack.append(cur.getList()[i])
        return False
# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())

# 栈，中等，每日一题。很有意思的题
# https://leetcode-cn.com/problems/flatten-nested-list-iterator/