[LeetCode] Maximum Depth of Binary Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    
    int result = 0;
    
    public int maxDepth(TreeNode root) {
        dfs(root, 1);
        return result;
    }
    
    public void dfs(TreeNode node, int depth) {
        if(node == null) {            
            return ;
        }
        
        if(node.left == null && node.right == null) {
            result = Math.max(result, depth);
        }
        
        dfs(node.left, depth + 1);
        dfs(node.right, depth + 1);
    }
}