/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* sortedListToBST(ListNode* head) {
        if(head==NULL)
            return NULL;
        vector<int> v;
        ListNode* p=head;
        while(p)
        {
            v.push_back(p->val);
            p=p->next;
        }
        return BuildTree(v,0,v.size()-1);
    }
    TreeNode* BuildTree(vector<int>& nums,int first,int end)
    {
        if(first>end)return NULL;
        if(first==end)return new TreeNode(nums[first]);
        int mid=(first+end)/2;
        TreeNode* root=new TreeNode(nums[mid]);
        root->left=BuildTree(nums,first,mid-1);
        root->right=BuildTree(nums,mid+1,end);
        return root;
    }
};