[leetcode]108. Convert Sorted Array to Binary Search Tree
Analysis
组会又被怼了—— [哎~]
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.
这题是用递归法构建一个平衡二叉树
平衡二叉树:a binary tree in which the depth of the two subtrees of every node never differ by more than 1.
Implement
/**
* 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.size()==0)
return NULL;
return myBST(nums, 0, nums.size()-1);
}
TreeNode* myBST(vector<int>& nums, int l, int r){
if(l > r)
return NULL;
int mid = (l+r)/2;
TreeNode* root = new TreeNode(nums[mid]);
root->left = myBST(nums, l, mid-1);
root->right = myBST(nums, mid+1, r);
return root;
}
};