Path Sum III is an example of tree problems. In this post we will see how we can solve in Javascript.

Problem Description

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes).

The tree has no more than 1,000 nodes and the values are in the range -1,000,000 to 1,000,000.

Example: 

root = [10,5,-3,3,2,null,11,3,-2,null,1], sum = 8

        10
       /  \
      5   -3
     / \    \
    3   2   11
   / \   \
  3  -2   1

Return 3. The paths that sum to 8 are:

  • 5 -> 3
  • 5 -> 2 -> 1
  • -3 -> 11

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!