將一個按照升序排列的有序數組,轉換爲一棵高度平衡二叉搜索樹。
本題中,一個高度平衡二叉樹是指一個二叉樹每個節點 的左右兩個子樹的高度差的絕對值不超過 1。
示例:
給定有序數組: [-10,-3,0,5,9],
一個可能的答案是:[0,-3,9,-10,null,5],它可以表示下面這個高度平衡二叉搜索樹:
0
/ \
-3 9
/ /
-10 5
來源:力扣(LeetCode)
鏈接:https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree
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/**
* Definition for a binary tree node.
* public class TreeNode {
* public int val;
* public TreeNode left;
* public TreeNode right;
* public TreeNode(int x) { val = x; }
* }
*/
public class Solution
{
public TreeNode SortedArrayToBST(int[] nums)
{
if (nums.Length == 0)
{
return null;
}
int left = 0;
int right = nums.Length - 1;
int mid = (left + right) / 2;
TreeNode Root = new TreeNode(nums[mid]);
Root.left = CreateBST(nums, 0, mid - 1);
Root.right = CreateBST(nums, mid + 1, right);
return Root;
}
public TreeNode CreateBST(int[] nums, int left, int right)
{
if (left > right)
{
return null;
}
int mid = (left + right) / 2;
TreeNode temp = new TreeNode(nums[mid]);
temp.left = CreateBST(nums, left, mid - 1);
temp.right = CreateBST(nums, mid + 1, right);
return temp;
}
}