1、DFS
import java.util.*; /* * public class TreeNode { * int val = 0; * TreeNode left = null; * TreeNode right = null; * } */ public class Solution { /** * * @param root TreeNode类 * @return int整型 */ public int maxDepth (TreeNode root) { // write code here return dfs(root); } private int dfs(TreeNode root) { if (root == null) { return 0; } int l = dfs(root.left); int r = dfs(root.right); return Math.max(l, r) + 1; } }