Linked list

double_linked_list.c

// Doubl Linked-List
#include <stdio.h>
#include <stdlib.h>

struct Element {
    char value;
    struct Element *next;
    struct Element *previous;
};

struct Element *first;

void insert_end(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;
    newItem->previous = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        while (temp->next != NULL) {
            temp = temp->next;
        }
        temp->next = newItem;
        newItem->previous = temp;
    }
}

void insert_beginning(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;
    newItem->previous = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        first = newItem;
        first->next = temp;
        temp->previous = first;
    }
}

void insert_custom(char itemToInsert, int position) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    }
    struct Element *temp = first;
    for (int i = 0; i < position && temp->next != NULL; ++i) {
        temp = temp->next;
    }
    newItem->next = temp->next;
    temp->next = newItem;

    newItem->next->previous = newItem;
    newItem->previous = temp;
}

void delete_end() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        while (temp->next->next != NULL) {
            temp = temp->next;
        }
        struct Element *last = temp->next;
        temp->next = NULL;
        free(last);
    }
}

void delete_beginning() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        first = first->next;
        first->previous = NULL;
        free(temp);
    }
}

void delete_custom(int position) {
    if (first == NULL)
        return;
    struct Element *temp = first;
    for (int i = 0; i < (position - 1) && temp->next->next != NULL; ++i) {
        temp = temp->next;
    }
    struct Element *last = temp->next;
    temp->next = last->next;
    temp->next->previous = temp;
    free(last);
}

queue.c

// Kinda messed up this queue. Enqueues at the head and dequeues at the tail.
// Queue implemented with Linked-List

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

struct Element {
    char value;
    struct Element *next;
};

struct Element *first;

void enqueue(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        first = newItem;
        first->next = temp;
    }
}

void dequeue() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        while (temp->next->next != NULL) {
            temp = temp->next;
        }
        struct Element *last = temp->next;
        temp->next = NULL;
        free(last);
    }
}

single.c

// Single Linked-List

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

struct Element {
    char value;
    struct Element *next;
};

struct Element *first;

void insert_end(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        while (temp->next != NULL) {
            temp = temp->next;
        }
        temp->next = newItem;
    }
}

void insert_beginning(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        first = newItem;
        first->next = temp;
    }
}

void insert_custom(char itemToInsert, int position) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    }
    struct Element *temp = first;
    for (int i = 0; i < position && temp->next != NULL; ++i) {
        temp = temp->next;
    }
    newItem->next = temp->next;
    temp->next = newItem;
}

void delete_end() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        while (temp->next->next != NULL) {
            temp = temp->next;
        }
        struct Element *last = temp->next;
        temp->next = NULL;
        free(last);
    }
}

void delete_beginning() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        first = first->next;
        free(temp);
    }
}

void delete_custom(int position) {
    if (first == NULL)
        return;
    struct Element *temp = first;
    for (int i = 0; i < (position - 1) && temp->next->next != NULL; ++i) {
        temp = temp->next;
    }
    struct Element *last = temp->next;
    temp->next = last->next;
    free(last);
}

stack.c

// Stack implemented with Linked List
#include <stdio.h>
#include <stdlib.h>

struct Element {
    char value;
    struct Element *next;
};

struct Element *first;

void push(char itemToInsert) {
    struct Element *newItem = (struct Element *)malloc(sizeof(struct Element));
    newItem->value = itemToInsert;
    newItem->next = NULL;

    if (first == NULL) {
        first = newItem;
    } else {
        struct Element *temp = first;
        first = newItem;
        first->next = temp;
    }
}

void pop() {
    if (first == NULL)
        return;
    else {
        struct Element *temp = first;
        first = first->next;
        free(temp);
    }
}