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.

 1 public class Solution {
 2     public boolean hasPathSum(TreeNode root, int sum) {
 3        if(root==null)
 4           return false;
 5         if(root.left==null&&root.right==null&&root.val ==sum) return true;
 6         else{
 7             return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);
 8         }
 9     }
10 }

View Code

Path Sum