這題是要找出二元搜尋樹有幾層，用深度搜尋法去找。
LeetCode 題目連結
https://leetcode.com/problems/maximum-depth-of-binary-tree/
題目
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.
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.
Accept 作法
Runtime: 0 ms
Memory: 39 MB
/**
* 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;
int resultLeft = maxDepth(root.left);
int resultRight = maxDepth(root.right);
return 1 + Math.max(resultLeft,resultRight);
}
}
更多 LeetCode 相關資源
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除了 LeetCode 練習外，我也入手了這本，題庫來自真正的面試，並非摘自教科書。它們反映出頂尖公司真正會出的題目，你可以藉此做好充分準備。
需要的話可以看看，寫得很仔細。
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