count total number of '0' , '1' and '2' * count [ 0 ] will store total number of '0' s * count [ 1 ] will store total number of '1' s * count [ 2 ] will store total number of '2' s
while ( ptr != NULL ) { count [ ptr -> data ] += 1 ; ptr = ptr -> next ; } int i = 0 ; ptr = head ;