Reverse a linkes list

struct node {
    int data ;
    struct node* next ;
}

// use pointer to node because we gotta change head reference value in function

void reverseList(node** head)
{
    struct node* current = *head;
    struct node* prev = NULL;
    struct node* next ;
   
   
    while( current != NULL)
    {
        //save next node
        next = current->next;
       
        //shift previous node , reversing two nodes at a time (current and previous)
        current->next = prev ;
        //update prev
        prev = current ;
       
        //update current pointing rest of the list
        current = next ;
       
    }
   
    //update head
    *head = prev ;
}


Simple Visualisation  inside loop

Sample linked list

1 -> 2 -> 3
Iterations :
1 :     1-> NULL (*prev == 1 )  , 2->3 (*current == 2)
2 :     2->1->NULL (*prev == 2) , 3-> NULL
3:     3->2->1-> (*prev == 3)  , NULL

Loop over  ,  update  *head = prev