```
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* reverseBetween(ListNode* head, int m, int n)
{
int count;
ListNode *prev = NULL,*next,*prev_m_1=NULL,*curr=head;
count = m-1;
if(m==n)
return head;
while(count)
{
prev_m_1 = curr;
curr = curr->next;
count--;
}
count = n - m + 1;
while(count)
{
//cout << curr->val<< endl;
next = curr->next;
curr->next = prev;
prev = curr;
curr = next;
count--;
}
if(prev_m_1)
{
prev_m_1->next->next = curr;
prev_m_1->next = prev;
return head;
}
head->next = curr;
return prev;
}
};
```