Most Frequent Subtree Sum is an example of tree problems. In this post we will see how we can solve in Javascript.

Problem Description

Given the root of a tree, you are asked to find the most frequent subtree sum. The subtree sum of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node itself). So what is the most frequent subtree sum value? If there is a tie, return all the values with the highest frequency in any order.

Example 1

Input:

 5
/ \
2 -3

return [2, -3, 4], since all the values happen only once, return all of them in any order.

Example 2

Input:

 5
/ \
2 -5

return [2], since 2 happens twice, however -5 only occur once.

Note: You may assume the sum of values in any subtree is in the range of 32-bit signed integer.

Solution: Please check the main.js snippet for the solution. If you have different approach in mind or have any suggestion for this implementation feel free to share in the comment below. Thanks!