题解 | #二叉树的最大深度#

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 {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @return int整型
     */
    public int maxDepth (TreeNode root) {
        // write code here
        int[] depth = new int[1];
        int i1 = 0;
        int i2 = 0;
        if (root != null) {
            depth[0]++;

            if (root.left != null) {
                i1 = depth(root.left, depth);
            }
            if (root.right != null) {
                i2 = depth(root.right, depth);
            }


        }
        return depth[0] + Math.max(i1, i2);
    }
    public int depth(TreeNode root, int[] depth) {
        
        int i1 = 0;
        int i2 = 0;
        if (root != null) {
            if (root.left != null) {
                i1 = depth(root.left, depth);
            }
            if (root.right != null) {
                i2 = depth(root.right, depth);
            }
        }

        return depth[0] + Math.max(i1, i2);


    }
}