Sum of all odd natural numbers in range L and R

Given two integers L and R, the task is to find the sum of all odd natural numbers in range L and R inclusive.

Examples:

Input: L = 2, R = 5
Output: 8
3 + 5 = 8

Input: L = 7, R = 13
Output: 40

A naive approach is to traverse from L to R and summate the elements to get the answer.

An efficient approach is to use the formula for calculating the sum of all odd natural numbers upto R and L-1 and then subtract sum(R)-sum(L-1).

Below is the implementation of the above approach:

C++

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// C++ program to print the sum
// of all numbers in range L and R
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the sum of
// all odd natural numbers
int sumOdd(int n)
{
    int terms = (n + 1) / 2;
    int sum = terms * terms;
    return sum;
}
  
// Function to return the sum
// of all odd numbers in range L and R
int suminRange(int l, int r)
{
    return sumOdd(r) - sumOdd(l - 1);
}
  
// Driver Code
int main()
{
    int l = 2, r = 5;
    cout << "Sum of odd natural numbers from L to R is "
         << suminRange(l, r);
  
    return 0;
}

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Java

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// Java program to print the sum
// of all numbers in range L and R
  
import java.io.*;
  
class GFG {
     
  
  
// Function to return the sum of
// all odd natural numbers
static int sumOdd(int n)
{
    int terms = (n + 1) / 2;
    int sum = terms * terms;
    return sum;
}
  
// Function to return the sum
// of all odd numbers in range L and R
static int suminRange(int l, int r)
{
    return sumOdd(r) - sumOdd(l - 1);
}
  
// Driver Code
public static void main (String[] args) {
            int l = 2, r = 5;
    System.out.print( "Sum of odd natural numbers from L to R is "
        + suminRange(l, r));
    }
}
// This code is contributed by shs..
  
  

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Python3

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# Python 3 program to print the sum 
# of all numbers in range L and R 
  
# Function to return the sum of 
# all odd natural numbers 
def sumOdd(n):
    terms = (n + 1)//2
    sum1 = terms * terms
    return sum1
  
# Function to return the sum 
# of all odd numbers in range L and R 
def suminRange(l, r):
    return sumOdd(r) - sumOdd(l - 1)
      
# Driver code
l = 2; r = 5
print("Sum of odd natural number",
      "from L to R is", suminRange(l, r))
  
# This code is contributed by Shrikant13

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C#

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// C# program to print the sum
// of all numbers in range L and R
using System;
  
class GFG 
{
      
// Function to return the sum of
// all odd natural numbers
static int sumOdd(int n)
{
    int terms = (n + 1) / 2;
    int sum = terms * terms;
    return sum;
}
  
// Function to return the sum
// of all odd numbers in range L and R
static int suminRange(int l, int r)
{
    return sumOdd(r) - sumOdd(l - 1);
}
  
// Driver Code
public static void Main () 
{
    int l = 2, r = 5;
    Console.WriteLine( "Sum of odd natural numbers "
                "from L to R is " + suminRange(l, r));
}
}
  
// This code is contributed by shs..

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PHP

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<?php
//PHP program to print the sum 
// of all numbers in range L and R 
// Function to return the sum of 
// all odd natural numbers 
function sumOdd($n
    $terms = (int)($n + 1) / 2; 
    $sum = $terms * $terms
    return $sum
  
// Function to return the sum 
// of all odd numbers in range L and R 
function  suminRange($l, $r
    return sumOdd($r) - sumOdd($l - 1); 
  
// Driver Code 
  
    $l = 2;
    $r = 5; 
    echo "Sum of odd natural numbers from L to R is ",
         suminRange($l, $r); 
  
?>

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Output:

Sum of odd natural numbers from L to R is 8


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Just another competitive programmer

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