求前N个自然数的平均值

编写程序以查找前N个自然数的平均值。
例子：

Input  : 10
Output : 5.5
1+2+3+4+5+6+7+8+9+10 = 5.5

Input  : 7
Output : 4.0
1+2+3+4+5+6+7 = 4

先决条件：前n个自然数之和。
如前所述，n个自然数的总和n(n + 1)/ 2，我们发现n个自然数的平均值，因此除以n为n(n + 1)/ 2 * n =(n + 1)/ 2。如果第一项为1，则n为最后一项。

C++

// CPP Program to find the Average of first
// n natural numbers
#include 
using namespace std;
 
// Return the average of first n natural numbers
float avgOfFirstN(int n)
{
    return (float)(1 + n)/2;
}
 
// Driven Program
int main()
{
    int n = 20;
    cout << avgOfFirstN(n) << endl;
    return 0;
}

Java

// Java Program to find the Average of first
// n natural numbers
import java.io.*;
 
class GFG {
 
    // Return the average of first n
    // natural numbers
    static float avgOfFirstN(int n)
    {
        return (float)(1 + n) / 2;
    }
 
    // Driven Program
    public static void main(String args[])
    {
        int n = 20;
        System.out.println(avgOfFirstN(n));
    }
}
 
/*This code is contributed by Nikita tiwari.*/

Python3

# Python 3 Program to find the Average
# of first n natural numbers
 
# Return the average of first n
# natural numbers
def avgOfFirstN(n) :
    return (float)(1 + n) / 2;
 
# Driven Program
n = 20
print(avgOfFirstN(n))
 
# This code is contributed by Nikita Tiwari.

C#

// C#Program to find the Average of first
// n natural numbers
using System;
 
class GFG {
 
    // Return the average of first n
    // natural numbers
    static float avgOfFirstN(int n)
    {
        return (float)(1 + n) / 2;
    }
 
    // Driven Program
    public static void Main()
    {
        int n = 20;
        Console.WriteLine(avgOfFirstN(n));
    }
}
 
/*This code is contributed by vt_m.*/

Javascript

 
// javascript Program to find the Average of first
// n natural numbers
 
// Return the average of first n natural numbers
function avgOfFirstN( n)
{
    return (1 + n)/2;
}
 
// Driven Program
 
    let n = 20;
    document.write(avgOfFirstN(n));
 
// This code is contributed by todaysgaurav
 

输出：

10.5

时间复杂度：O(1)