LeetCode: Deepest Leaves Sum Solution

1/**
2 * Definition for a binary tree node.
3 * function TreeNode(val, left, right) {
4 *     this.val = (val===undefined ? 0 : val)
5 *     this.left = (left===undefined ? null : left)
6 *     this.right = (right===undefined ? null : right)
7 * }
8 */
9/**
10 * @param {TreeNode} root
11 * @return {number}
12 */
13var deepestLeavesSum = function (root) {
14  let maxDepth = 0
15  let deepestLeavesSum = 0
16
17  const assignDepth = (node, depth = 0) => {
18    if (!node) return
19
20    maxDepth = Math.max(maxDepth, depth)
21    node.depth = depth
22    assignDepth(node.left, depth + 1)
23    assignDepth(node.right, depth + 1)
24  }
25  const getSum = node => {
26    if (!node) return
27
28    if (node.depth === maxDepth) deepestLeavesSum += node.val
29    getSum(node.left)
30    getSum(node.right)
31  }
32
33  assignDepth(root)
34  getSum(root)
35
36  return deepestLeavesSum
37}
38
39var deepestLeavesSum = function (root) {
40  let maxDepth = 0
41  const depthSum = {}
42
43  const traverse = (node, depth = 0) => {
44    if (!node) return
45
46    depthSum[depth] = (depthSum[depth] || 0) + node.val
47    maxDepth = Math.max(maxDepth, depth)
48    traverse(node.left, depth + 1)
49    traverse(node.right, depth + 1)
50  }
51
52  traverse(root)
53
54  return depthSum[maxDepth]
55}