LeetCode:Convert Sorted Array to Binary Search Tree

Prolem:

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

Subscribe to see which companies asked this question

Solution:

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
//二分运用
class Solution {
public:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        
        return generateTree(0,nums.size()-1,nums);
        
    }
    
    TreeNode* generateTree(int left,int right,vector<int>& nums)
    {
        if(left>right) return NULL;
        else if(left==right) return new TreeNode(nums[left]);
        else
        {
            int middle=(left+right)/2;
            TreeNode *root=new TreeNode(nums[middle]);
            root->left=generateTree(left,middle-1,nums);
            root->right=generateTree(middle+1,right,nums);
            return root;
        }
    }
};