The maximum depth of the binary tree algorithm endless

Given a binary tree to find its maximum depth.

The depth of the binary tree is the root node to the nodes on the longest path farthest leaf node.

Description: leaf node is a node has no child nodes.

Example:

Given binary tree [3,9,20, null, null, 15,7],

    3
   / \
  9  20
    /  \
   15   7

Return to its maximum depth of 3.

Ideas:

Dfs depth-first traversal use recursion to solve.

answer:

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    int max=0;
    int temp=0;
    public int maxDepth(TreeNode root) {
        if(root==null){
            return 0;
        }
        int leftDeepth=maxDepth(root.left);
        int rightDeepth=maxDepth(root.right);
        return Math.max(leftDeepth,rightDeepth)+1;
    }
}