nested-list-weight-sum-ii.py

# Time:  O(n)
# Space: O(h)

# """
# 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 Solution(object):
    def depthSumInverse(self, nestedList):
        """
        :type nestedList: List[NestedInteger]
        :rtype: int
        """
        def depthSumInverseHelper(list, depth, result):
            if len(result) < depth + 1:
                result.append(0)
            if list.isInteger():
                result[depth] += list.getInteger()
            else:
                for l in list.getList():
                    depthSumInverseHelper(l, depth + 1, result)
                    
        result = []
        for list in nestedList:
            depthSumInverseHelper(list, 0, result)

        sum = 0
        for i in reversed(xrange(len(result))):
            sum += result[i] * (len(result) - i)
        return sum