Leetcode | | 108. Convert Sorted Array to Binary Search Tree

Problem:

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

Hide TagsTree Depth-first SearchTest instructions: Converts an ascending sequence into a balanced lookup binary tree

Thinking:

(1) Balanced binary tree concept: The height difference of the left and right sub-tree can not exceed 1, find the concept of binary tree: Left child < parent < child

(2) Two-way recursive construction of two-fork tree

(3) The template function solves the formal parameter type Vector<int>::iterator is too long, the writing is inconvenient

Code

Class Solution {public  :      TreeNode *sortedarraytobst (vector<int> &num) {          if (num.size () ==0)              return NULL;          Return make (Num.begin (), Num.end ());                }      Template<class it>      TreeNode *make (it first,it last)      {          if (first==last)              return NULL;          It loc = first+ (Last-first)/2;          TreeNode *node = new TreeNode (*loc);          Node->left=make (first,loc);          Node->right=make (loc+1,last);          return node;      }  };

Leetcode | | 108. Convert Sorted Array to Binary Search Tree