Leetcode-Algorithms Nested List Weight Sum

最新推荐文章于 2021-11-10 11:22:10 发布

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本文介绍了一种计算Nested List中所有整数的加权和的方法，其中权重由元素的深度决定。通过递归遍历列表并累加每个整数及其对应的深度权重，实现了对复杂嵌套列表的有效处理。

Given a nested list of integers, return the sum of all integers in the list weighted by their depth.

Each element is either an integer, or a list – whose elements may also be integers or other lists.

Example 1:
Given the list [[1,1],2,[1,1]], return 10. (four 1’s at depth 2, one 2 at depth 1)

Example 2:
Given the list [1,[4,[6]]], return 27. (one 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4*2 + 6*3 = 27)

求一个nested list权重和.

# """
# 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
        """

        if len(nestedList) == 0: 
            return 0

        stack = []
        total_weight = 0
        for lst in nestedList:
            stack.append((lst,1))   #add initial weight for lst

        while(stack):
            lst, w = stack.pop(0)   #get 1st lst and the weight in stack

            #if is integer, time weight and add to total weight
            if lst.isInteger():
                total_weight += lst.getInteger() * w

            #if it is not integer, get all the elements in the list and each weight plus 1
            else:
                for child in lst.getList():
                    stack.append((child,w+1))

        return total_weight