题目
给你一个整数数组 nums ,其中元素已经按 升序 排列,请你将其转换为一棵
平衡
二叉搜索树。
示例 1:
输入:nums = [-10,-3,0,5,9]
输出:[0,-3,9,-10,null,5]
解释:[0,-10,5,null,-3,null,9] 也将被视为正确答案:
解
java
class Solution {
public TreeNode sortedArrayToBST(int[] nums) {
return dfs(nums, 0, nums.length - 1);
}
public TreeNode dfs(int[] nums, int left, int right) {
if (left > right) {
return null;
}
int mid = left + (right - left) / 2;
TreeNode leftNode = dfs(nums, left, mid - 1);
TreeNode root = new TreeNode(nums[mid]);
root.left = leftNode;
root.right = dfs(nums, mid + 1, right);
return root;
}
}