gistfile1.txt

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

struct list_node
{
	const char * name;
	list_node* next;
};

void print( list_node* head )
{
	while( head!= NULL ){
		printf( "%s ", head->name );
		head= head->next;
	}
	printf( "\n" );
}

list_node* last( list_node * head )
{
	while( head->next != NULL )
		head= head->next;
	return head;
}

list_node * find_in_queue( list_node * head, const char* names[], int n )
{
	list_node* result = NULL;

	while( head != NULL ) {
		for( int i=0; i < n; ++i ) {
			const char* name = names[i];
			if( name == NULL )continue;

			if( strcmp( head->name, name ) == 0 ) {
				if( result == NULL ) result = head;

				names[i] = NULL;
			}
		}
		head= head->next;
	}
	return result;
}

list_node* create_node( const char* name )
{
	list_node* new_node = (list_node*)malloc( sizeof list_node );
	new_node->name = name;
	new_node->next = NULL;
	return new_node;
}

list_node* add_after( list_node* after_this, const char* name )
{
	list_node* new_node =create_node( name );
	new_node->next = after_this->next;
	after_this->next= new_node;
	return new_node;
}

void add_guests_after( list_node* after_this, const char* names[], int n )
{
	for( int i=0; i < n; ++i ) {
		const char* name = names[i];
		if( name == NULL )continue;

		after_this= add_after( after_this, name );
	}
}

void add_guests( list_node* queue_head, const char* names[], int n )
{
	list_node* found = NULL;
	
	found = find_in_queue( queue_head, names, n );
	if( found == NULL )
		found = last( queue_head );

	add_guests_after( found, names, n );
}

list_node* create_ABCD()
{
	list_node* queue_head = create_node( "A" );
	list_node* iterator = queue_head;

	iterator = add_after( iterator, "B" );
	iterator = add_after( iterator, "C" );
	iterator = add_after( iterator, "D" );
	return queue_head;
}

void test_simple_create()
{
	list_node* queue_head = create_ABCD();

	print( queue_head );
}

void test_add_end()
{
	list_node* queue_head = create_ABCD();

	const char* guests[3] ={ "X", "Y", "Z" };
	add_guests( queue_head, guests, 3 );
	print( queue_head );
}

void test_add_one_middle()
{
	list_node* queue_head = create_ABCD();

	const char* guests[3] ={ "X", "C", "Z" };
	add_guests( queue_head, guests, 3 );
	print( queue_head );
}

void test_add_repeated()
{
	list_node* queue_head = create_ABCD();

	const char* guests[3] ={ "D", "C", "A" };
	add_guests( queue_head, guests, 3 );
	print( queue_head );
}

int main() {
	test_simple_create();
	puts( "-----" );
	test_add_end();
	puts( "-----" );
	test_add_one_middle();
	puts( "-----" );
	// broken
	test_add_repeated();
}