108. Convert Sorted Array to Binary Search Tree

标签：bin   ble   treenode   中间   height   this   arch   search   OWIN   

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

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example:

Given the sorted array: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

      0
     /    -3   9
   /   /
 -10  5

class Solution {
    public TreeNode sortedArrayToBST(int[] nums) {
        if(nums.length == 0) return null;
        return help(nums, 0, nums.length - 1);
    }
    public TreeNode help(int[] nums, int start, int end){
        int l = end - start;
        if(l < 0) return null;
        int mid = (start + end) / 2;
        TreeNode root = new TreeNode(nums[mid]);
        root.left = help(nums, start, mid - 1);
        root.right = help(nums,mid+1, end);
        return root;
    }
}

没什么特殊的，每一步都是把中间的当作root，然后两边作为subtree。

108. Convert Sorted Array to Binary Search Tree

标签：bin   ble   treenode   中间   height   this   arch   search   OWIN   

原文地址：https://www.cnblogs.com/wentiliangkaihua/p/10504814.html