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Nested List Weight Sum (for E4)

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As we can see from the source image, this question is from LC339 :)

The other question asked together was LC636 :)

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.

Examples
01 · Example 1
nestedList = [[1,1],2,[1,1]]
return = 10
Example 1 illustration

Four 1's at depth 2, one 2 at depth 1. 1*2 + 1*2 + 2*1 + 1*2 + 1*2 = 10.

02 · Example 2
nestedList = [1,[4,[6]]]
return = 27
Example 2 illustration

One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3. 1*1 + 4*2 + 6*3 = 27.

03 · Example 3
nestedList = [0]
return = 0

There is one 0 at depth 1. 0*1 = 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.
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public int depthSum(List<NestedInteger> nestedList) {
  // write your code here
}
nestedList[[1,1],2,[1,1]]
expected10
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