Q:
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
Analysis:
题目要求将已升序的数组转化为二叉排序树;可以使用递归,二分的方法,进行生成二叉排序树。
Code:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public TreeNode sortedArrayToBST(int[] nums) {
if (nums == null) {
return null;
}
int start = 0;
int end = nums.length - 1;
return sortedArrayToBST(nums, start, end);
}
public static TreeNode sortedArrayToBST(int[] nums, int start, int end) {
TreeNode root = null;
if (start > end) {
return null;
}
int mid = (start + end) / 2;
root = new TreeNode(nums[mid]);
root.left = sortedArrayToBST(nums, start, mid - 1);
root.right = sortedArrayToBST(nums, mid + 1, end);
return root;
}
}