LeetCode108 Convert Sorted Array to Binary Search Tree
Given an array where elements are sorted in ascending order, convert it to a height balanced BST. (Medium)
分析:
因为要构成BBST,所以要从中点开始,左边为左子树,右边为右子树,采用helper函数传递初始结束两个参数,递归求解即可。
代码:
/**
* 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 {
private:
TreeNode* helper(vector<int>& nums, int start, int end) {
if (start >= end) {
return nullptr;
}
int mid = start + (end - start) / ;
TreeNode* root = new TreeNode(nums[mid]);
root -> left = helper(nums, start, mid);
root -> right = helper(nums, mid + , end);
return root;
}
public:
TreeNode* sortedArrayToBST(vector<int>& nums) {
TreeNode* result = helper(nums, , nums.size());
return result;
}
};
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