Convert Sorted Array to Binary Search Tree

1.题目描述

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

 

2.解法分析

如果是数组，这个题目就是个二分查找的过程，不断寻找当前的树根。

/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: TreeNode *sortedArrayToBST(vector<int> &num) { // Start typing your C/C++ solution below // DO NOT write int main() function int len = num.size(); if(!len)return NULL; return mySortedArrayToBST(num,0,len-1); } TreeNode *mySortedArrayToBST(vector<int> &num,int start,int end) { if(start>end)return NULL; int mid = (start+end)/2; TreeNode * parent = new TreeNode(num[mid]); parent->left = mySortedArrayToBST(num,start,mid-1); parent->right = mySortedArrayToBST(num,mid+1,end); } };