LeetCode题解：Convert Sorted Array to Binary Search Tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

题意：给定一个升序数组，将它转换为二叉搜索树

解决思路：二分……

代码：

public class Solution {
public TreeNode sortedArrayToBST(int[] num) {
if (num.length == 0) {
return null;
}
TreeNode head = helper(num, 0, num.length - 1);
return head;
}

public TreeNode helper(int[] num, int low, int high) {
if (low > high) { // Done
return null;
}
int mid = (low + high) / 2;
TreeNode node = new TreeNode(num[mid]);
node.left = helper(num, low, mid - 1);
node.right = helper(num, mid + 1, high);
return node;
}
}