//1
#include <stdio.h>
#include <string.h>
#include <math.h>

int main()
{
    int guests;
    float chairs, persons, cups, dishes, totalPrice = 0;

    char objects[50];

    printf("Enter guests: ");
    scanf("%d", &guests);

    printf("Enter an object: ");
    scanf("%s", &objects);

    while (strcmp(objects, "PARTY!") != 0)
    {
        if (strcmp(objects, "Chair") == 0)
        {
            totalPrice += 13.99;
            chairs += 1;
        }
        else if (strcmp(objects, "Table") == 0)
        {
            totalPrice += 42.00;
            persons += 8;
        }
        else if (strcmp(objects, "Cups") == 0)
        {
            totalPrice += 5.98;
            cups += 6;
        }
        else if(strcmp(objects, "Dishes") == 0)
        {
            totalPrice += 21.02;
            dishes += 6;
        }

        printf("Enter an object: ");
        scanf("%s", &objects);
    }

    printf("Total price: %.2f\n", totalPrice);
    float neededChairs = guests - chairs;
    float neededPlacesOnTables = guests - persons;
    float neededCups = guests - cups;
    float neededDishes = guests - dishes;

    if (neededChairs > 0)
    {
        printf("%d Chairs\n", neededChairs);
    }

    if (neededCups > 0)
    {
        float cupsComplect = ceil(neededCups / 6);

        if (cupsComplect == 0)
        {
            cupsComplect = 1;
        }
        printf("%.0f Cups\n", neededCups);
    }

    if (neededPlacesOnTables > 0)
    {
        float neededTables = ceil(neededPlacesOnTables / 8);

        if (neededTables == 0)
        {
            neededTables = 1;
        }

        printf("%.0f Tables\n", neededTables);
    }

    if (neededDishes > 0)
    {
        float neededDishesComplekt = ceil(neededDishes / 6);

        if (neededDishesComplekt == 0)
        {
            neededDishesComplekt = 1;
        }

        printf("%.0f Dishes\n", neededDishesComplekt);
    }

    return 0;
}

//2
#include <stdio.h>
#include <string.h>

typedef struct
{
    char name[50];
    float price;
    int uniqueProductNum;
} Product;

typedef struct
{
    char address[50];
    int productNum;
} Order;

Product* remove(Product* products, int size, int index);

int main()
{
    char option[50];
    printf("Choose: Product/Order: ");
    scanf("%s", option);

    Product* products;
    int index = 0;
    int sizeArr = 0;

    while (strcmp(option, "END") != 0)
    {
        if (strcmp(option, "Product") == 0)
        {
            Product currentStudent;

            printf("Enter product name: ");
            scanf("%s", currentStudent.name);

            printf("Enter price: ");
            scanf("%f", &currentStudent.price);

            printf("Enter product number: ");
            scanf("%d", &currentStudent.uniqueProductNum);

            products[index] = currentStudent;
            index++;
            sizeArr++;
        }

        else if (strcmp(option, "Order") == 0)
        {
            Order currentOrder;

            printf("Enter address: ");
            scanf("%s", currentOrder.address);

            printf("Enter product number: ");
            scanf("%d", &currentOrder.productNum);

            int size = sizeArr;

            for (int i = 0; i < size; i++)
            {
                if (products[i].uniqueProductNum == currentOrder.productNum)
                {
                    Product product = products[i];
                    products = remove(products, size, i);
                    printf("Client %s ordered %s\n", currentOrder.address , product.name);

                    sizeArr--;
                }
            }
        }

        printf("Choose: Product/Order: ");
        scanf("%s", option);
    }

    printf("------------\n");

    for (int i = 0; i < sizeArr; i++)
    {
        printf("Name: %s\n", products[i].name);
        printf("Price: %.2f\n", products[i].price);
        printf("Product number: %d\n", products[i].uniqueProductNum);
    }

    return 0;
}

  Product* remove(Product* products, int size, int index)
    {
        Product* newPorducts = (Product*)malloc(size * sizeof(Product));

        for (int i = 0; i < size; i++)
        {
            if (i < index)
            {
                newPorducts[i] = products[i];
            }

            else if (i > index)
            {
                newPorducts[i - 1] = products[i];
            }
        }

        return newPorducts;
    }

//3
#include <stdio.h>
#include <stdlib.h>
#include <string.h>



int main()
{

    FILE* fp = fopen("input.txt", "rt");
    FILE* fpout = fopen("output.bin", "wb");

    char word[50];
    int resultsize = 0;
    char *result = malloc(0);


    char lastChar = 0;

    for(;;)
    {

        if(fscanf(fp, "%s", word) == EOF)
            break;

        if(lastChar == 0 || lastChar == word[0])
        {

            lastChar = word[strlen(word)-1];
            result = realloc(result, (++resultsize) * 50);
            memcpy(&result[(resultsize-1)*50], &word, strlen(word)+1);
            printf("%s - %d - %c - %c\n", word, strlen(word), word[strlen(word)-1], word[0]);

        }


    }

    fwrite(result, 1, resultsize * 50, fpout);


    return 0;
}

input.txt -
apple car price elephant head tire cool soft eleven output night tent story movies pleasure memory time search shortcut river compare evening

//4

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

int main() {
  int key;
  char input_file_name[100], output_file_name[100];
  FILE *input_file, *output_file;

  printf("Enter key: ");
  scanf("%d", &key);
  if (key < 2 || key > 10) {
    printf("Invalid key. Please try again!\n");
    return 1;
  }
  printf("Enter input file: ");
  scanf("%s", input_file_name);
  printf("Enter output file: ");
  scanf("%s", output_file_name);

  input_file = fopen(input_file_name, "r");
  if (input_file == NULL) {
    printf("Error while opening the input file!\n");
    return 1;
  }
  output_file = fopen(output_file_name, "w");
  if (output_file == NULL) {
    printf("Error while opening the output file!\n");
    return 1;
  }

  char c;
  while ((c = fgetc(input_file)) != EOF) {
    if (c >= 'a' && c <= 'z') {
      c = 'a' + (c - 'a' + key) % 26;
    } else if (c >= 'A' && c <= 'Z') {
      c = 'A' + (c - 'A' + key) % 26;
    }
    fputc(c, output_file);
  }

  fclose(input_file);
  fclose(output_file);

  printf("Success!\n");
  return 0;
}

//5
#include <stdio.h>
#include <string.h>

int main() {
    char word[50], dashes[50], letter;
    int length, i, j, guesses, maxGuesses, found = 0;

    printf("Enter word: ");
    scanf("%s", word);
    length = strlen(word);

    for (i = 0; i < length; i++) {
        dashes[i] = '_';
    }
    dashes[length] = '\0';

    maxGuesses = length + 2;

    while (guesses < maxGuesses) {
        printf("\n%s\n", dashes);
        printf("Enter letter: ");
        scanf(" %c", &letter);

        found = 0;
        for (i = 0; i < length; i++) {
            if (word[i] == letter) {
                dashes[i] = letter;
                found = 1;
            }
        }

        if (!found) {
            printf("No match with that letter!\n");
            guesses++;
        }

        if (strcmp(word, dashes) == 0) {
            printf("You have guessed the \"%s\" word!\n", word);
            printf("Attempts: %d\n", guesses);
            return 0;
        }
    }

    printf("You lost! The word is \"%s\".\n", word);
    printf("Attempts: %d\n", guesses);

    return 0;
}


//6
#include <stdio.h>
#include <string.h>

int findAnagram(char* str1, char* str2) {
    int len1 = strlen(str1);
    int len2 = strlen(str2);
    if (len1 != len2) {
        return 0;
    }

    int char_count[256] = {0};

    for (int i = 0; i < len1; i++) {
        char_count[str1[i]]++;
    }

    for (int i = 0; i < len2; i++) {
        char_count[str2[i]]--;
    }

    for (int i = 0; i < 256; i++) {
        if (char_count[i] != 0) {
            return 0;
        }
    }

    return 1;
}

int main() {
    char word1[50], word2[50];
    printf("Enter word 1: ");
    scanf("%s", word1);
    printf("Enter word 2: ");
    scanf("%s", word2);

    printf("%d\n", findAnagram(word1, word2));

    return 0;
}

//7
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    int id;
    float hourlyPrice;
    float hoursPerWeek;
    float salaryPerWeek;
} Employee;

void addEmployee(Employee* employees, int* employees);
void getSalary(Employee* employee);
void print(Employee* employees, int employees);

int main() {
    Employee employees[30];
    int employees, choice = 0;

    while (choice != 3) {
        printf("Menu:\n");
        printf("1. Add employee\n");
        printf("2. Print employees\n");
        printf("3. Exit\n");
        printf("Enter choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                addEmployee(&employees[employees], &employees);
                break;
            case 2:
                print(employees, employees);
                break;
            case 3:
                printf("Goodbye!\n");
                break;
            default:
                printf("Invalid choice\n");
                break;
        }
    }

    FILE* fp = fopen("employees.bin", "wb");
    if (fp == NULL) {
        printf("Error opening file\n");
        return 1;
    }

    fwrite(employees, sizeof(Employee), employees, fp);

    fclose(fp);

    return 0;
}

void addEmployee(Employee* employees, int* employees) {
    if (*employees >= MAX_EMPLOYEES) {
        printf("Maximum number of employees reached\n");
        return;
    }

    Employee new_employee;
    printf("Enter ID: ");
    scanf("%d", &new_employee.id);
    printf("Enter hourly pay: ");
    scanf("%f", &new_employee.hourlyPrice);
    printf("Enter weekly hours: ");
    scanf("%f", &new_employee.hoursPerWeek);

    getSalary(&new_employee);

    employees[*employees] = new_employee;
    (*employees)++;
}

void getSalary(Employee* employee) {
    if (employee->hoursPerWeek > 40) {
        employee->salaryPerWeek = 40 * employee->hourlyPrice
            + (employee->hoursPerWeek - 40) * employee->hourlyPrice * 1.5;
    } else {
        employee->salaryPerWeek = employee->hoursPerWeek * employee->hourlyPrice;
    }

    float taxes = employee->salaryPerWeek * 0.0365;
    employee->salaryPerWeek -= taxes;
}

void print(Employee* employees, int employees) {
    printf("ID\tHourly Pay\tWeekly Hours\tWeekly Salary\n");
    printf("-------------------------------------------------\n");
    for (int i = 0; i < employees; i++) {
        printf("%d\t%.2f\t\t%.2f\t\t%.2f\n",
            employees[i].id, employees[i].hourlyPrice,
            employees[i].hoursPerWeek, employees[i].salaryPerWeek);
    }
}