You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists.
The depth of an integer is the number of lists that it is inside of. For example, the nested list [1,[2,2],[[3],2],1] has each integer's value set to its depth.
Return the sum of each integer in nestedList multiplied by its depth.
Example 1:
Input: nestedList = [[1,1],2,[1,1]]
Output: 10
Explanation: Four 1's at depth 2, one 2 at depth 1. 1*2 + 1*2 + 2*1 + 1*2 + 1*2 = 10.
Example 2:
Input: nestedList = [1,[4,[6]]]
Output: 27
Explanation: One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3. 1*1 + 4*2 + 6*3 = 27.
Example 3:
Input: nestedList = [0]
Output: 0
Constraints:
1 <= nestedList.length <= 50
The values of the integers in the nested list is in the range [-100, 100].
The maximum depth of any integer is less than or equal to 50.
分析： dfs
# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
#class NestedInteger:
# def __init__(self, value=None):
# """
# If value is not specified, initializes an empty list.
# Otherwise initializes a single integer equal to value.
# """
#
# def isInteger(self):
# """
# @return True if this NestedInteger holds a single integer, rather than a nested list.
# :rtype bool
# """
#
# def add(self, elem):
# """
# Set this NestedInteger to hold a nested list and adds a nested integer elem to it.
# :rtype void
# """
#
# def setInteger(self, value):
# """
# Set this NestedInteger to hold a single integer equal to value.
# :rtype void
# """
#
# def getInteger(self):
# """
# @return the single integer that this NestedInteger holds, if it holds a single integer
# The result is undefined 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
# The result is undefined if this NestedInteger holds a single integer
# :rtype List[NestedInteger]
# """
class Solution:
def depthSum(self, nestedList: List[NestedInteger]) -> int:
def dfs(nestedList, level):
if nestedList.isInteger():
return level*nestedList.getInteger()
res = 0
for nested in nestedList.getList():
res += dfs(nested, level+1)
return res
res = 0
for i in nestedList:
res += dfs(i, 1)
return res
