339 Nested List Weight Sum
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)

Algorithm

Traverse the given nested linked list array, for each nested linked list object, call the dfs function, assign a depth value of 1, and add up and return.
In the dfs function, first determine whether it is an integer,

If yes, it returns the current depth multiplied by an integer

If not, then we traverse the nested array again, call the recursive function for each nested linked list, and add up the return value to return