[leetcode] 108. Convert Sorted Array to Binary Search Tree 解题报告

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题目链接:https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/

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


思路:前面有一题将有序链表转换为平衡二叉搜索树的,思路都一样,递归的二分数组,取数组中间的一个数为根,左边的为左子树,右边的为右子树。

今天去看了一场昆汀的电影,叫什么来着《The Hateful Eight》没有字幕,看着好蛋疼啊,睡了前半段,到最后也没搞明白这电影讲的啥,只记得各种爆头再见

代码如下:

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


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