每次从中间分割数组
import java.util.*;
/*
* public class TreeNode {
* int val = 0;
* TreeNode left = null;
* TreeNode right = null;
* }
*/
public class Solution {
/**
*
* @param num int整型一维数组
* @return TreeNode类
*/
public TreeNode sortedArrayToBST(int[] nums) {
return sortedArrayToBST(nums, 0, nums.length - 1);
}
public TreeNode sortedArrayToBST(int[] nums, int left, int right) {
if (left >= right) {
return left > right ? null : new TreeNode(nums[left]);
}
int mid = left + (right - left) / 2;
TreeNode root = new TreeNode(nums[mid]);
TreeNode leftNode = sortedArrayToBST(nums, left, mid - 1);
TreeNode rightNode = sortedArrayToBST(nums, mid + 1, right);
root.left = leftNode;
root.right = rightNode;
return root;
}
}