Demo C/C++

#include <iostream>
using namespace std;

int bai_1(int n)
{
    int s = 0;
    for (int i = 1; i <= n; i++)
        s += i;
    return s;
}

int bai_2(int n)
{
    int s = 0;
    for (int i = 1; i <= n; i++)
        s += i * i;
    return s;
}

float bai_3(int n)
{
    float s = 0;
    for (int i = 1; i <= n; i++)
        s += 1.0f / i;
    return s;
}

float bai_4(int n)
{
    float s = 0;
    for (int i = 1; i <= n; i++)
        s += 1.0f / (2 * i);
    return s;
}


float bai_5(int n)
{
    float s = 0;
    for (int i = 0; i <= n; i++)
        s += 1.0f / (2 * i + 1);
    return s;
}

float bai_6(int n)
{
    float s = 0;
    for (int i = 1; i <= n; i++)
        s += 1.0f / (i * (i + 1));
    return s;
}

float bai_7(int n)
{
    float s = 0;
    for (int i = 1; i <= n; i++)
        s += i * 1.0f / (i + 1);
    return s;
}
float bai_8(int n)
{
    float s = 0;
    for (int i = 1; i <= n; i++)
        s += (2 * i + 1) * 1.0f / (2 * i + 2);
    return s;
}


void main()
{
    int n = 5;
    cout << "Bai 1: \n\tn = " << n << "\n\tKet qua: " << bai_1(n) << endl;
    cout << "Bai 2: \n\tn = " << n << "\n\tKet qua: " << bai_2(n) << endl;
    cout << "Bai 3: \n\tn = " << n << "\n\tKet qua: " << bai_3(n) << endl;
    cout << "Bai 4: \n\tn = " << n << "\n\tKet qua: " << bai_4(n) << endl;
    cout << "Bai 5: \n\tn = " << n << "\n\tKet qua: " << bai_5(n) << endl;
    cout << "Bai 6: \n\tn = " << n << "\n\tKet qua: " << bai_6(n) << endl;
    cout << "Bai 7: \n\tn = " << n << "\n\tKet qua: " << bai_7(n) << endl;
    cout << "Bai 8: \n\tn = " << n << "\n\tKet qua: " << bai_8(n) << endl;
}