void BuildBST(int* array, int start, int end, Node *&node)
{
if (end - start == 1)
{
Node* rightNode = new Node{ nullptr, nullptr, array[end] };
node = new Node{ nullptr, rightNode, array[start] };
return;
}
if (end == start)
{
node = new Node{ nullptr, nullptr, array[start] };
return;
}
int middle = (start + end) / 2;
if (node == nullptr)
{
node = new Node{ nullptr, nullptr, array[middle] };
}
else
{
node->Value = array[middle];
}
BuildBST(array, start, middle - 1, node->Left);
BuildBST(array, middle + 1, end, node->Right);
}
TreeNode* BuildBST(ListNode*& list, int start, int end) { // DO NOT FORGET & !!!
if (start > end) return NULL;
int mid = (start + end) / 2; //if use start + (end - start) >> 1, test case will break, strange!
TreeNode* leftChild = BuildBST(list, start, mid - 1);
TreeNode* parent = new TreeNode(list->val);
parent->left = leftChild;
list = list->next;
parent->right = BuildBST(list, mid + 1, end);
return parent;
}
int _tmain(int argc, _TCHAR* argv[])
{
int input[size] = { 0, 1, 2, 3, 4, 5 };
Node* root = new Node();
BuildBST(input, 0, size - 1, root);
return 0;
}
TreeNode* sortedListToBST(ListNode* head) {
int len = 0;
ListNode* p = head;
while (p) {
len++;
p = p->next;
}
return BuildBST(head, 0, len - 1);
}
