answer.py

#!/usr/bin/env python3

#-------------------------------------------------------------------------------	
# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
#class NestedInteger(object):
#    def isInteger(self):
#        """
#        @return True if this NestedInteger holds a single integer, rather than a nested list.
#        :rtype bool
#        """
#
#    def getInteger(self):
#        """
#        @return the single integer that this NestedInteger holds, if it holds a single integer
#        Return None if this NestedInteger holds a nested list
#        :rtype int
#        """
#
#    def getList(self):
#        """
#        @return the nested list that this NestedInteger holds, if it holds a nested list
#        Return None if this NestedInteger holds a single integer
#        :rtype List[NestedInteger]
#        """

class NestedIterator(object):

    def __init__(self, nestedList):
        """
        Initialize your data structure here.
        :type nestedList: List[NestedInteger]
        """
        self.flatlist = []
        self.idx = 0
        self.addLists(nestedList)


    def next(self):
        """
        :rtype: int
        """
        if self.hasNext:
            self.idx += 1
            return self.flatlist[self.idx-1]

    def hasNext(self):
        """
        :rtype: bool
        """
        return self.idx < len(self.flatlist)
        
    def addLists(self, nest):
        for element in nest:
            if not element.isInteger():
                self.addLists(element.getList())
            else:
                self.flatlist.append(element.getInteger())
  

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