queue.cpp

// queue2.cpp : Этот файл содержит функцию "main". Здесь начинается и заканчивается выполнение программы.
// Удалить любой элемент из однонаправленной очереди

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

struct queue
{
    char* str;
    struct queue* next;
};

void add_elemenet(struct queue** head, struct queue** tail, char* str)
{
    struct queue* temp = (struct queue*)malloc(sizeof(struct queue));
    temp->str = (char*)malloc(sizeof(char) * (strlen(str) + 1));
    strcpy(temp->str, str);
    temp->next = NULL;

    if (*head == NULL)
    {
        *head = *tail = temp;
        return;
    }

    temp->next = *tail;
    *tail = temp;
}

void show_queue(struct queue* tail)
{
    if (!tail)
    {
        return;
    }

    do
    {
        puts(tail->str);
        tail = tail->next;
    } while (tail);

    fprintf(stdout, "\n\n");
}

void dequeue(struct queue** head, struct queue** tail) //first element remove
{
    if (!*head)
    {
        return;
    }

    if (*head == *tail)
    {
        free((*head)->str);
        free(*head);
        *head = *tail = NULL;
        return;
    }

    struct queue* temp = *tail;

    while (temp->next != *head)
    {
        temp = temp->next;
    }

    *head = temp;
    free(temp->next->str);
    free(temp->next);
    temp->next = NULL;
}

void remove_any(struct queue** head, struct queue** tail, char* str)
{
    if (!head)
    {
        return;
    }

    if (*tail == *head)
    {
        if (strcmp((*head)->str, str) == 0)
        {
            free((*head)->str);
            free(*head);
            *head = *tail = NULL;
        }

        return;
    }

    struct queue* cur = *tail;
    struct queue* prev;

    while (*tail && strcmp(cur->str, str) == 0)
    {
        *tail = (*tail)->next;
        free(cur->str);
        free(cur);
        cur = *tail;
    }

    cur = (*tail)->next;
    prev = *tail;

    while (cur)
    {
        if (strcmp(cur->str, str) == 0)
        {
            if (cur == *head)
            {
                *head = prev;
                (*head)->next = NULL;
                free(cur->str);
                free(cur);
                return;
            }

            prev->next = cur->next;
            free(cur->str);
            free(cur);
            cur = prev->next;
        }
        else
        {
            prev = cur;
            cur = cur->next;
        }
    }
}

int main()
{
    struct queue* head = NULL, *tail = NULL;

    char* str = NULL;

    for(;;)
    {
        str = (char*)malloc(sizeof(char) * 100);
        gets_s(str, 100);
        if (str[0] == '\0' )
        {
            free(str);
            break;
        }
        add_elemenet(&head, &tail, str);
        free(str);
    }

    show_queue(tail);

    dequeue(&head, &tail);

    show_queue(tail);

    str = (char*)malloc(sizeof(char) * 100);
    gets_s(str, 100);

    remove_any(&head, &tail, str);

    show_queue(tail);

    free(str);

    return 0;
}