stck.c

#include <stdio.h>

#define STACK_SIZE 10

enum state { OK = 0, UNDERFLOW = -1, OVERFLOW = -2 };

int stack[STACK_SIZE];
int top = 0;

int stack_push(int x) {
	if (top == STACK_SIZE) return OVERFLOW;

	stack[top] = x;
	top++;
	return OK;

}

int stack_pop(void) {
	if (top == 0) return UNDERFLOW;

	top--;
	int res = stack[top];
	stack[top] = 0;
	return res;

}

int stack_state(void) {
	return top;
}

// FIFO queue with shifts

#define QUEUE_SIZE 10

int queue[QUEUE_SIZE];
int in = 0, curr_nr = 0;

int queue_push(int in_nr) { // in_nr clients try to enter the queue
	int overflow = 0;
	
	for (int i = 0; i < in_nr; i++){
		curr_nr++;
		if (in == QUEUE_SIZE) overflow = 1;
		else{
			queue[in] = curr_nr;
			in++;
		}
	}
	if (overflow) return OVERFLOW;
	else return 0;
}

int queue_pop(int out_nr) { // out_nr clients leaves the queue
	if (out_nr > in){
		in = 0;
		return UNDERFLOW;
	}

	while (out_nr){
		for (int j = 0; j < QUEUE_SIZE - 1; j++){
			queue[j] = queue[j + 1];
		}
		out_nr--;
		in--;
	}

	return in;
	}

int queue_state(void) {
	return in;
}

void queue_print(void) {
	for (int i = 0; i < in; i++){
		printf("%d ", queue[i]);
	}
	printf("\n");
}

// Queue with cyclic buffer

#define CBUFF_SIZE 10

int cbuff[CBUFF_SIZE];
int out = 0, len = 0;


int cbuff_push(int cli_nr) { // client with number cli_nr enters the queue
	if (len == CBUFF_SIZE) return OVERFLOW;
	cbuff[(out + len) % CBUFF_SIZE] = cli_nr;
	len++;
	return OK;
}

int cbuff_pop(void) { // longest waiting client leaves the queue
	if (len == 0) return UNDERFLOW;
	int res = cbuff[out];
	out = (out + 1) % CBUFF_SIZE;
	len--;
	return res;
}

int cbuff_state(void) {
	return len;
}

void cbuff_print(void) {
	for (int i = out; i < len + out; i++){
		printf("%d ", cbuff[i % CBUFF_SIZE]);
	}
	printf("\n");
}

int main(void) {
	int to_do, n, client_no, answer;
	scanf("%d", &to_do);
	switch(to_do) {
		case 1: // stack
			do {
				scanf("%d", &n);
				if (n > 0) {
					if ((answer = stack_push(n)) < 0) printf("%d ", answer);
				} else if (n < 0) {
					printf("%d ", stack_pop());
				} else printf("\n%d\n", stack_state());
			} while(n != 0);
			break;
		case 2: // FIFO queue with shifts
			do {
				scanf("%d", &n);
				if (n > 0) {
					if ((answer = queue_push(n)) < 0) printf("%d ", answer);
				} else if (n < 0) {
					if ((answer = queue_pop(-n)) < 0) printf("%d ", answer);
				} else {
					printf("\n%d\n", queue_state());
					queue_print();
				}
			} while(n != 0);
			break;
		case 3: // queue with cyclic buffer
			client_no = 0;
			do {
				scanf("%d", &n);
				if (n > 0) {
					if ((answer = cbuff_push(++client_no)) < 0) printf("%d ", answer);
				} else if (n < 0) {
					printf("%d ", cbuff_pop());
				} else {
					printf("\n%d\n", cbuff_state());
					cbuff_print();
				}
			} while(n != 0);
			break;
		default: 
			printf("NOTHING TO DO!\n");
	}
	return 0;
}