Convert_Sorted_List_To_BST.cpp

class Solution {
public:
    TreeNode *sortedListToBST(ListNode *head)
    {
    	return sortedListToBST( head, NULL );
    }

private:
    TreeNode *sortedListToBST(ListNode *head, ListNode *tail)
    {
    	if( head == tail )
    		return NULL;
    	if( head->next == tail )    //
    	{
    		TreeNode *root = new TreeNode( head->val );
    		return root;
    	}
    	ListNode *mid = head, *temp = head;
    	while( temp != tail && temp->next != tail )    // 寻找中间节点
    	{
    		mid = mid->next;
    		temp = temp->next->next;
    	}
    	TreeNode *root = new TreeNode( mid->val );
    	root->left = sortedListToBST( head, mid );
    	root->right = sortedListToBST( mid->next, tail );
    	return root;
    }
};