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Copy path108.ConvertSortedArrayToBinarySearchTree.cpp
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108.ConvertSortedArrayToBinarySearchTree.cpp
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44 lines (39 loc) · 1.21 KB
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// Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
//Code:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode* sortedArrayToBST(vector<int>& nums) {
if(nums.empty()) return nullptr;
std::function<TreeNode* (int, int)>
sortedArrayToBSTHelper = [&](int start, int end)->TreeNode*
{
if(start > end) return nullptr;
if(start == end) return new TreeNode(nums[start]);
int mid = start + (end - start) / 2;
TreeNode* root = new TreeNode(nums[mid]);
root->left = sortedArrayToBSTHelper(start, mid - 1);
root->right = sortedArrayToBSTHelper(mid + 1, end);
return root;
};
auto root = sortedArrayToBSTHelper(0, nums.size() - 1);
return root;
}
};