LeetCode--Path Sum

題目：

解決方案：

/**
 * 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;}
            }

        return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);

    }
}