LeetCode108 Convert Sorted Array to Binary Search Tree


描述

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

样例

1

思路

将有序数组转成二叉搜索树。

由于是有序数组,每次在中间位置将数组分成左右两部分递归下去即可。

代码

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/**
* 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* build(vector<int>& nums, int l, int r) {
if (l > r) return NULL;
int mid = l + (r - l + 1) / 2;
TreeNode* root = new TreeNode(nums[mid]);
root->left = build(nums, l, mid - 1);
root->right = build(nums, mid + 1, r);
return root;
}
TreeNode* sortedArrayToBST(vector<int>& nums) {
return build(nums, 0, nums.size() - 1);
}
};