341. Flatten Nested List Iterator

# """
# 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:
    
    def __init__(self, nestedList: [NestedInteger]):
        self.stack = list(reversed(nestedList))
        
        
    def next(self) -> int:
        self.make_stack_top_an_integer()
        return self.stack.pop().getInteger()
    
        
    def hasNext(self) -> bool:
        self.make_stack_top_an_integer()
        return len(self.stack) > 0
        
        
    def make_stack_top_an_integer(self):
        # While the stack contains a nested list at the top...
        while self.stack and not self.stack[-1].isInteger():
            # Unpack the list at the top by putting its items onto
            # the stack in reverse order.
            self.stack.extend(reversed(self.stack.pop().getList()))
         

# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())

Runtime: 68 ms, faster than 59.60% of Python3 online submissions for Flatten Nested List Iterator.
Memory Usage: 17.8 MB, less than 30.38% of Python3 online submissions for Flatten Nested List Iterator.

이런 문제 나오면 저 울어요...^^
자주 안나온다는데에 희망을 걸어 봅시다.