【题目】
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
/ \
9 20
/ \
15 7
return its depth = 3.
【思路】
递归，1+Math.max(maxDepth(root.left),maxDepth(root.right));
【解答】
class Solution {
public int maxDepth(TreeNode root) {
if(root==null)
return 0;
return 1+Math.max(maxDepth(root.left),maxDepth(root.right));
}
}
【其他定义】
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
/** * 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(root==null) return 0; return 1+Math.max(maxDepth(root.left),maxDepth(root.right)); } }