104. Maximum Depth of Binary Tree
Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Note: A leaf is a node with no children.
Example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 920 /\ 157 return its depth = 3.
難度:easy
題目:給定二叉樹,找出最大深度。
最大深度指的是最長路徑從根結點到最遠的葉子結點。
思路:後序遍歷
Runtime: 0 ms, faster than 100.00% of Java online submissions for Maximum Depth of Binary Tree.
Memory Usage: 27.8 MB, less than 73.06% of Java online submissions for Maximum Depth of Binary Tree.
/** * Definition for a binary tree node. * public class TreeNode { *int val; *TreeNode left; *TreeNode right; *TreeNode(int x) { val = x; } * } */ class Solution { public int maxDepth(TreeNode root) { if (null == root) { return 0; } return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1; } }