112. Path Sum.js

// Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum.

// A leaf is a node with no children.

// Example 1:

// Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
// Output: true
// Explanation: The root-to-leaf path with the target sum is shown.
// Example 2:

// Input: root = [1,2,3], targetSum = 5
// Output: false
// Explanation: There two root-to-leaf paths in the tree:
// (1 --> 2): The sum is 3.
// (1 --> 3): The sum is 4.
// There is no root-to-leaf path with sum = 5.
// Example 3:

// Input: root = [], targetSum = 0
// Output: false
// Explanation: Since the tree is empty, there are no root-to-leaf paths.

const hasPathSum = (root, targetSum) => {
	if (root == null) return false

	if (root.val == targetSum && root.left == null && root.right == null)
		return true

	return (
		hasPathSum(root.left, targetSum - root.val) ||
		hasPathSum(root.right, targetSum - root.val)
	)
}