339. Nested List Weight Sum

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.

Rust Solution

struct Solution;
use rustgym_util::*;

impl Solution {
    fn depth_sum_r(nested_list: &NestedInteger, level: i32) -> i32 {
        match nested_list {
            NestedInteger::Int(x) => level * x,
            NestedInteger::List(v) => v
                .iter()
                .fold(0, |acc, x| acc + Self::depth_sum_r(x, level + 1)),
        }
    }
    fn depth_sum(nested_list: Vec<NestedInteger>) -> i32 {
        nested_list
            .iter()
            .fold(0, |acc, x| acc + Self::depth_sum_r(x, 1))
    }
}

#[test]
fn test() {
    let list = vec![
        nested_integer!("[1,1]"),
        nested_integer!("2"),
        nested_integer!("[1,1]"),
    ];
    assert_eq!(Solution::depth_sum(list), 10);
    let list = vec![nested_integer!("1"), nested_integer!("[4,[6]]")];
    assert_eq!(Solution::depth_sum(list), 27);
}

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