【LeetCode】104. Maximum Depth of Binary Tree

Difficulty:easy

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Description

https://leetcode.com/problems/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.

Intuition

1.Recursion

 

Solution

    public int maxDepth(TreeNode root) {
        if(root==null)
            return 0;
        return Math.max(maxDepth(root.left), maxDepth(root.right))+1;
    }

　　

Complexity

Time complexity : O(n)

Space complexity : O(logn)

  

 More:【目錄】LeetCode Java實現