3.cpp

#include <stdio.h>
#include <stdlib.h>
#define MAX_SIZE 200
int arr[MAX_SIZE];

typedef struct alfa *alfaptr;

struct alfa
{
    long long x;
    alfaptr next;
};
alfaptr rear = NULL, front = NULL;
void push(int x)
{
    alfaptr node;
    node = (alfaptr)malloc(sizeof(struct alfa));
    node->x = x;
    node->next = NULL;
    if (!front)
    {
        front = node;
        rear = node;
    }
    else
    {
        rear->next = node;
        rear = node;
    }
}

void pop()
{
    alfaptr node;
    if (!front)
        printf("ERROR1");
    else
    {
        node = front->next;
        delete front;
        front = node;
    }
}
void search(int x)
{
    alfaptr node = front;
    int counter = 0;
    while (node)
    {
        if (node->x == x)
            printf("Found in %d\n", counter);
        node = node->next;
        counter++;
    }
}

void rpop()
{ // pop last element
    alfaptr node = front;
    while (node->next)
    {
        rear = node;
        node = node->next;
    }
    free(node);
}

void set()
{
    alfaptr node = front;
    for (int i = 0; i < MAX_SIZE && node; i++, node = node->next)
        arr[i] = node->x;
}

int size()
{
    alfaptr node = front;
    int count;
    while (node)
    {
        count++;
        node = node->next;
    }
    return count;
}

void show()
{
    if (!front)
    {
        for (int i = 0; i < MAX_SIZE; i++)
            printf("%d ", arr[i]);
    }
    else
    {
        printf("ERROR3");
    }
}

int average()
{

    alfaptr node = front;
    int sum = 0, count;
    while (node)
    {
        sum += node->x;
        count++;
        node = node->next;
    }
    return sum / count;
}

int main()
{
    int cmd;
    long long int x;
    while (true)
    {
        scanf("%d", &cmd);
        switch (cmd)
        {
        case 1: // push
            scanf("%lld", &x);
            push(x);
            break;
        case 2: // pop
            pop();
            break;
        case 3: // rpop
            rpop();
            break;
        case 4: // search
            scanf("%lld", &x);
            search(x);
            break;
        case 5: // set
            set();
            break;
        case 6: // show
            show();
            break;
        case 7: // size
            printf("%d", size());
            break;
        case 10:
            exit(0);
        }
    }
}