C :

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

struct list{
    char studentNo[16];
    struct list *next;
};
typedef struct list Sqlist;

int funQuery(Sqlist*, const char*);
Sqlist* funPrintAll(Sqlist*);
Sqlist* funInsert(Sqlist*, const char*);
Sqlist* funDelete(Sqlist*, const char*);

int main()
{
	int tmp, i;
	char command[16];
	Sqlist *head[128];
	
	for (i = 0; i < 128; i++){
		head[i] = (Sqlist*)malloc(sizeof (Sqlist));
		head[i]->next = NULL;
	}
	
	while (scanf("%s", command) && strcmp(command, "end")){
		
		switch (command[0]){
			case '+':
				head[command[1]] = funInsert(head[command[1]], &command[1]);
				break;
			case '-':
				head[command[1]] = funDelete(head[command[1]], &command[1]);
				break;
			case '?':
				tmp = funQuery(head[command[1]], &command[1]);
				if (tmp){
					printf("yes\n");
				}else{
					printf("no\n");
				}
				break;
		}
	}
	
	for (i = 0; i < 128; i++){
		head[i] = funPrintAll(head[i]);
		free(head[i]);
		head[i] = NULL;
	}
	
	return 0;
}

Sqlist* funPrintAll(Sqlist* head)
{
	Sqlist *q, *p;
	p = head;
	q = p->next;
	while (q != NULL){
		printf("%s\n", q->studentNo);
		p = q;
		q = p->next;
		free(p);
	}
	return head;
}

int funQuery(Sqlist* head, const char* stuNo)
{
	int tmp;
	Sqlist *q;
	q = head;
	while (q = q->next){
		if (q == NULL){
			break;
		}
		tmp = strcmp(q->studentNo, stuNo);
		if (!tmp){
			return 1;
		}
		if (tmp > 0){
			return 0;
		}
	}
	return 0;
}

Sqlist* funInsert(Sqlist* head, const char* stuNo)
{
	int tmp;
	Sqlist *p, *q, *s;
	p = head;
	while (q = p->next){
		if (q == NULL){
			break;
		}
		tmp = strcmp(q->studentNo, stuNo);
		if (!tmp){
			return head;
		}
		if (tmp < 0){
			p = q;
		}else{
			break;
		}
	}
	s = (Sqlist*)malloc(sizeof (Sqlist));
	strcpy(s->studentNo, stuNo);
	s->next = q;
	p->next= s;
	
	return head;
}

Sqlist* funDelete(Sqlist* head, const char* stuNo)
{
	int tmp;
	Sqlist *p, *q;
	p = head;
	while (q = p->next){
		if (q == NULL){
			break;
		}
		tmp = strcmp(q->studentNo, stuNo);
		if (!tmp){
			p->next = q->next;
			free(q);
		}
		if (tmp < 0){
			p = q;
		}else{
			break;
		}
	}
	
	return head;
}