c的练习

int function(int number) {
    int result = 1;
    if (number <= 1)
    return result;
    result = number * function(number - 1);
}

int main()
{
    int a = 0;
    cin >> a;
    cout << function(a) << endl;
    return 0;
}

void HeapAdjust(int *data, int s, int len) {
    int temp = *(data + s);
    for (int j = 2 * s; j < len; j *= 2) {
        if (j < len && *(data + j) < *(data + j + 1)) {
            j++;
        }
        if (temp > *(data + j)) {
            break;
        }
        *(data + s) = *(data + j);
        s = j;
    }
    *(data + s) = temp;
}

void swap(int *data, int a, int b) {
    int temp = 0;
    temp = *(data + a);
    *(data + a) = *(data + b);
    *(data + b) = temp;
}

int main() {
    int data[8] = { 4,2,3,7,8,1,11,5 };
    int len = 8;
    for (int i = (len - 1) / 2; i >= 0; i--) {
        HeapAdjust(data, i, len);
    }
    for (int i = len - 1; i >= 1; i--) {
        swap(data, 0, i);
        HeapAdjust(data, 0, i - 1);
    }
    for (int i = 0; i < len; i++) {
        cout << data[i] <<endl;
    }

    return 0;
}

void swap(int *data, int a, int b) {
    int temp = 0;
    temp = *(data + a);
    *(data + a) = *(data + b);
    *(data + b) = temp;
}

int Partition(int *data, int low, int high) {
    int temp = *(data + low);

    while (low < high) {
        while (low < high && *(data + high) >= temp) {
            high--;
        }
        swap(data, low, high);
        while (low < high && *(data + low) <= temp) {
            low++;
        }
        swap(data, low, high);
    }
    return low;
}

void QuickSort(int *data, int low, int high) {
    int partition_value = 0;
    if (low < high) {
        partition_value = Partition(data, low, high);
        QuickSort(data, low, partition_value - 1);
        QuickSort(data, partition_value + 1, high);
    }
}

int BinarySearch(int *data, int len, int key) {
    int mid = 0;
    int low = 0;
    int high = len - 1;

    while (low <= high) {
        mid = (low + high) / 2;

        if (*(data + mid) < key) {
            low = mid + 1;
        }
        else if (*(data + mid) > key) {
            high = mid - 1;
        }
        else {
            return mid;
        }
    }
    return 0;
}

int main() {
    int num[] = { 2,4,6,8,9,12,34 };

    cout << BinarySearch(num, 7, 2) << endl;
}

int main() {
    unsigned int num = 60;
    int count = 0;
    while (num != 0) {
        if (num % 2 == 1) {
            count++;
        }
        num /= 2;
    }
    cout << count << endl;
    return 0;
}

int gcd(int x, int y) {
    if (y == 0) {
        return x;
    }
    else {
        gcd(y, x%y);
    }
}

int main() {
    int x = 0, y = 0;
    cin >> x >> y;
    cout << gcd(x, y) << endl;
    return 0;
}

int main() {
    #define MAXLENGTH 200
    char input[MAXLENGTH] = { 0 };
    char c = getchar();
    int count = 0;
    int input_len = 0;

    while (c != 'n') {
        input[count] = c;
        c = getchar();
        count++;
    }
    input_len = count;

    char input_spec[MAXLENGTH] = { 0 };
    int input_spec_len[MAXLENGTH] = { 0 };
    int spec_len = 0;

    input_spec[0] = input[0];
    input_spec_len[0] = 1;
    spec_len = 1;

    for (int i = 1; i < input_len; i++) {
        for (int j = 0; j < spec_len; j++) {
        if (input[i] == input_spec[j]) {
            input_spec_len[j]++;
            break;
        }
        if (input[i] != input_spec[j] && j == spec_len - 1) {
            input_spec[spec_len] = input[i];
            input_spec_len[spec_len]++;
            spec_len++;
            break;
        }
        }
    }

    double div_pro = 0;
    for (int i = 0; i < spec_len; i++) {
        double pro = (double)(input_spec_len[i]) / (double)(input_len);
        div_pro += (-1)*pro * log2(pro);
    }

    //cout << div_pro << endl;
    printf("%lf", div_pro);

    return 0;
}