题解 | #二叉树的深度#先序遍历二叉树

import java.util.*;
/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {

    public int TreeDepth(TreeNode root) {
        return preOrder(root, 0);
    }

    //先序遍历二叉树,根->左->右 每层+1,返回左节点和右节点最大的值即可
    public int preOrder(TreeNode root, int depth) {
        if (root == null) {
            return depth;
        }
        depth++;
        return Math.max(preOrder(root.left, depth), preOrder(root.right, depth));
    }
}