nested-list-weight-sum.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 depthSum(self, nestedList):
        """
        :type nestedList: List[NestedInteger]
        :rtype: int
        """
        def depthSumHelper(nestedList, depth):
            res = 0
            for l in nestedList:
                if l.isInteger():
                    res += l.getInteger() * depth
                else:
                    res += depthSumHelper(l.getList(), depth + 1)
            return res
        return depthSumHelper(nestedList, 1)