【LeetCode】Convert Sorted Array to Binary Search Tree 解题报告

【LeetCode】Convert Sorted Array to Binary Search Tree 解题报告

标签（空格分隔）： LeetCode

题目地址：https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/#/description

题目描述：

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

Ways

因为BST的中序遍历是有序的，所以有序数组的中间的数字是根节点，序列中间节点左边是根节点的左子树，右边是根节点的右子树，以此类推。

/**
* 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) {
return helper(nums, 0, nums.length - 1);
}

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

Date

2017 年 4 月 24 日