How should I practice Nested List Weight Sum (for E4)?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Meta phone screen and onsite interview problems in FastPrep.

Is Nested List Weight Sum (for E4) associated with Meta?

FastPrep tags this as a Meta phone screen and onsite interview coding practice problem when the problem catalog has that company and stage context.

Nested List Weight Sum (for E4)

Meta● EasyFULLTIMEPHONE SCREENONSITE INTERVIEW

Learn

Problem statement

You are given a valid JSON string nestedList encoding a nested list of integers. Each list element is an integer or another list. Return the sum of every integer multiplied by the number of enclosing lists. Integers directly inside the outer list have depth 1.

For this exercise, use the JSON text as the portable input representation. Spaces may occur between tokens. Empty inner lists contribute zero. The outer list has between 1 and 50 elements, integer values are from -100 through 100, and integer depth is at most 50.

Function

depthSum(nestedList: String) → int

Examples

Example 1

nestedList = "[[1,1],2,[1,1]]"return = 10

Four 1s are at depth 2, and 2 is at depth 1. The weighted sum is 1 × 2 + 1 × 2 + 2 × 1 + 1 × 2 + 1 × 2 = 10.

Example 2

nestedList = "[1,[4,[6]]]"return = 27

The value 1 is at depth 1, 4 is at depth 2, and 6 is at depth 3. The weighted sum is 1 × 1 + 4 × 2 + 6 × 3 = 27.

Example 3

nestedList = "[0]"return = 0

The value 0 is at depth 1, so the weighted sum is 0 × 1 = 0.

Constraints

The string is valid nested-list JSON containing only integer values, lists, commas, and optional spaces.
The decoded outer list contains 1 through 50 elements.
Every integer is in [-100,100], and maximum integer depth is 50.
For this exercise, assume the JSON text has at most 100000 characters.