[Leetcode] Path Sum

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:

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean hasPathSum(TreeNode root, int sum) {
        return dfs(root,sum,0);
    }

    private boolean dfs(TreeNode root, int sum, int curSum) {
        // TODO Auto-generated method stub
        if(root==null)
            return false;
        if(root.left==null&&root.right==null)
            return (curSum+root.val)==sum;
        return dfs(root.left,sum,curSum+root.val)||dfs(root.right, sum, curSum+root.val);
    }
}