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 / \ 9 20 / \ 15 7
return its depth = 3.
终极无敌之递归
class Solution { public int maxDepth(TreeNode root) { if(root == null) return 0; return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1; } }
或者联动Mindepth的方法,检查左右子节点是否为空,一一判断
class Solution { public int maxDepth(TreeNode root) { if(root == null) return 0; if(root.left == null) return 1+maxDepth(root.right); if(root.right == null) return 1+maxDepth(root.left); return 1+Math.max(maxDepth(root.right),maxDepth(root.left)); } }