Convert Sorted Array to Binary Search Tree
Problem Statement - link #
Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.
Examples #
Example 1:
Input: nums = [-10,-3,0,5,9]
Output: [0,-3,9,-10,null,5]
Explanation: [0,-10,5,null,-3,null,9] is also accepted:
Example 2:
Input: nums = [1,3]
Output: [3,1]
Explanation: [1,null,3] and [3,1] are both height-balanced BSTs.
Constraints #
1 <= nums.length <= 10^4-10^4 <= nums[i] <= 10^4numsis sorted in a strictly increasing order.
Solutions #
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
TreeNode* convertintoBST(vector<int> &nums,int left,int right) {
if(left > right) return NULL;
int mid = left+(right-left)/2;
TreeNode *node = new TreeNode(nums[mid]);
node->left = convertintoBST(nums,left,mid-1);
node->right = convertintoBST(nums,mid+1,right);
return node;
}
TreeNode* sortedArrayToBST(vector<int>& nums) {
if(nums.size() == 0) return NULL;
return convertintoBST(nums,0,nums.size()-1);
}
};