Convert Sorted Array to Binary Search Tree [LeetCode]
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
Summary: pretty easy, recursive staff.
1 class Solution { 2 public: 3 TreeNode *sortedArrayToBST(vector<int> &num) { 4 int size = num.size(); 5 if(size == 0) 6 return NULL; 7 if(size == 1) 8 return new TreeNode(num[0]); 9 if(num.size() % 2 == 1) { 10 TreeNode * root = new TreeNode(num[size/2]); 11 if(size/2 - 1 >= 0){ 12 vector<int> left(num.begin(), num.begin() + size/2); 13 root->left = sortedArrayToBST(left); 14 } 15 if(size/2 + 1 < size) { 16 vector<int> right(num.begin() + size/2 + 1, num.end()); 17 root->right = sortedArrayToBST(right); 18 } 19 return root; 20 }else { 21 TreeNode * root = new TreeNode(num[size/2 - 1]); 22 if(size/2 - 1 - 1 >= 0){ 23 vector<int> left(num.begin(), num.begin() + size/2 - 1); 24 root->left = sortedArrayToBST(left); 25 } 26 if(size/2 - 1 + 1 < size) { 27 vector<int> right(num.begin() + size/2 -1 + 1, num.end()); 28 root->right = sortedArrayToBST(right); 29 } 30 return root; 31 } 32 } 33 };
