LR15 AKT

int main()
{
    int countLine = 0, countNumber = 0, x;
    char s[20], c;
    FILE *f;
    fopen_s(&f, "test.txt", "r");

    setlocale(0, ".1251");

    /* Задание 1 */
    while (!feof(f)) {
        fgets(s, 20, f);
        countLine++;
    }
    printf("Колиество строк: %d\n", countLine);

    /* Задание 2 */
    bool a = false;
    fseek(f, 0, 0);
    countLine = 0;

    puts("\nСтроки, у которых первый и последний символ равны:");
    while (!feof(f)) {
        fgets(s, 20, f);
        countLine++;
        c = s[strlen(s) - 1];

        if(c == 10)
            c = s[strlen(s) - 2];

        if (c == s[0]) {
            a = true;
            printf("%d\n", countLine);
        }
    }

    if (a == false)
        puts("Таких строк нет.");

    /* Задание 3 */
    int *arr = NULL, i = 0;
    fseek(f, 0, 0);
    countLine = 0;

    puts("\nСамые коротки строки: ");
    while (!feof(f)) {
        fscanf_s(f, "%d", &x);
        countNumber++;

        c = fgetc(f);
        if ((int)c == 10 || feof(f))
        {
            countLine++;
            if (i < 2 || arr[0] > countNumber) {
                i = 2;
                arr = (int*)calloc(i, sizeof(int));
                arr[0] = countNumber;
                arr[1] = countLine;
            }else if(arr[0] == countNumber){
                i++;
                arr = (int*)realloc(arr, i * sizeof(int));
                arr[i - 1] = countLine;
            }

            countNumber = 0;
        }
    }

    for (int j = 1; j < i; j++) {
        if (j != 1) printf(", ");
        printf("%d", arr[j]);
    }
    free(arr);

    /* Задание 4 */
    puts("\n\nОдинаковые строки:");
    int **lines = (int**)malloc(sizeof(int**));
    lines[0] = NULL;
    fseek(f, 0, 0);
    countLine = 0;
    countNumber = 0;
    a = false;
    arr = (int*)malloc(sizeof(int));
    arr[0] = 0;

    while (!feof(f)) {
        if (fscanf_s(f, "%d", &x)) {
            countNumber++;
            lines[countLine] = (int*)realloc(lines[countLine], (countNumber + 1) * sizeof(int));
            lines[countLine][0] = countNumber;
            lines[countLine][countNumber] = x;
        }

        c = fgetc(f);
        if ((int)c == 10 || feof(f))
        {
            countLine++;
            lines = (int**)realloc(lines, (countLine + 1) * sizeof(int*));
            lines[countLine] = NULL;
            countNumber = 0;
        }
    }

    for (int i = 0; i < countLine - 1; i++) {
        int k;
        for (k = 1; k <= arr[0]; k++)
            if (i == arr[k])
                break;

        if (k != arr[0] + 1)
            continue;

        int d = 0;
        for (int j = i + 1; j < countLine; j++) {
            if (lines[i][0] == lines[j][0]) {
                int l;
                for (l = 1; l <= lines[i][0]; l++)
                    if (lines[i][l] != lines[j][l])
                        break;

                if (l == lines[i][0] + 1) {
                    if (d == 0)
                        printf("Строка %d идентина строкам: ", i+1);
                    else
                        printf(", ");

                    printf("%d", j+1);
                    d++;

                    arr[0]++;
                    arr = (int*)realloc(arr, (arr[0] + 1) * sizeof(int));
                    arr[arr[0]] = j;
                    a = true;
                }
            }
        }
        if (d != 0)
            puts("");
    }
    if (a == false)
        puts("Таких строк нет.");

    for (int i = 0; i < countLine; i++) {
        free(lines[i]);
    }
    free(lines);
    free(arr);

    /* Задание 5 */
    puts("\nМаксимальное значение строк:");
    int max;
    fseek(f, 0, 0);
    countLine = 0;
    countNumber = 0;
    while (!feof(f)) {
        fscanf_s(f, "%d", &x);
        if (countNumber == 0 || x > max)
            max = x;

        countNumber++;

        c = fgetc(f);
        if ((int)c == 10 || feof(f))
        {
            countLine++;
            countNumber = 0;
            printf("%d) %d\n", countLine, max);
        }
    }

    /* Задание 6 */
    puts("\nНомера введенного элемента:");
    int n;
    fseek(f, 0, 0);
    countLine = 0;
    countNumber = 0;
    a = false;

    printf("Введите элемент: ");
    scanf_s("%d", &n);

    while (!feof(f)) {
        if (countNumber == 0)
            printf("%d) ", countLine + 1);

        fscanf_s(f, "%d", &x);
        countNumber++;

        if (x == n) {
            printf("%d ", countNumber);
            a = true;
        }

        c = fgetc(f);
        if ((int)c == 10 || feof(f))
        {
            countLine++;
            countNumber = 0;
            if (a == false)
                printf("Такого элемента нет.");

            puts("");
            a = false;
        }
    }

    fclose(f);
}