**Problem:**

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:

Given the below binary tree and `sum = 22`

,

5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1

return true, as there exist a root-to-leaf path `5->4->11->2`

which sum is 22.

**Solution:**

Remember root to **leaf**.

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root, int sum) { if (root == null) return false; if (sum - root.val == 0 && root.left == null && root.right == null) return true; return (hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val)); } }