Maximum Depth of Binary Tree

Maximum Depth of Binary Tree

Description

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 1:
Given binary tree [3,9,20,null,null,15,7],

    3
   / \
  9  20
    /  \
   15   7

Tags: Tree

解读题意

获取一个二叉树的最大深度

思路1

通过递归方式来寻找最长的分支线，+1是要算上根结点。递归顺序为3 9 20 15 7，故time complexity为O(n)

class Solution {
       public int maxDepth(TreeNode root) {

        if (null == root) {
            return 0;
        } else {
            int i = maxDepth(root.left);
            int j = maxDepth(root.right);
            return (i < j) ? j + 1 : i + 1;
        }
    }
}

time complexity:O(n)

leetCode汇总：https://blog.youkuaiyun.com/qingtian_1993/article/details/80588941

项目源码，欢迎star：https://github.com/mcrwayfun/java-leet-code