https://oj.leetcode.com/problems/path-sum/

Path Sum.java

/**
 * 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) {
        if (root == null) return false;
        if ((root.left == null) && (root.right == null)){
            if (sum == root.val){
                return true;
            }else{
                return false;
            }
        }else{
            boolean ret = false;
            if (root.left != null) ret = ret || hasPathSum(root.left, sum - root.val);
            if (root.right != null) ret = ret || hasPathSum(root.right, sum - root.val);
            return ret;
        }
    }
}