Find the sum of the first half and second half elements of an array

Given an array arr of size N. The task is to find the sum of the first half (N/2) elements and second half elements (N – N/2) of an array.

Examples:

Input : arr[] = {20, 30, 60, 10, 25, 15, 40}
Output : 110, 90
Sum of first N/2 elemets 20 + 30 + 60 is 110

Input : arr[] = {50, 35, 20, 15}
Output : 85, 35

Approach:
Initialize SumFirst and SumSecond as 0. Traverse the given array and add elements in SumFirst if the current index is less than N/2 otherwise add in SumSecond.

Below is the implementation of the above approach:

C++

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// C++ program to find the sum of the first half
// elements and second half elements of an array
#include <bits/stdc++.h>
using namespace std;
  
// Function to find the sum of the first half
// elements and second half elements of an array
void sum_of_elements(int arr[], int n)
{
    int sumfirst = 0, sumsecond = 0;
  
    for (int i = 0; i < n; i++) {
        // Add elements in first half sum
        if (i < n / 2)
            sumfirst += arr[i];
  
        // Add elements in the second half sum
        else
            sumsecond += arr[i];
    }
  
    cout << "Sum of first half elements is " << 
                                   sumfirst << endl;
  
    cout << "Sum of second half elements is " << 
                                   sumsecond << endl;
}
  
// Driver Code
int main()
{
    int arr[] = { 20, 30, 60, 10, 25, 15, 40 };
  
    int n = sizeof(arr) / sizeof(arr[0]);
  
    // Function call
    sum_of_elements(arr, n);
  
    return 0;
}

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Java

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// Java program to count pairs 
// whose sum divisible by 'K' 
import java.util.*;
  
class GFG 
{
  
public static void sum_of_elements(int []arr, 
                                   int n)
    int sumfirst = 0, sumsecond = 0;
      
    for (int i = 0; i < n; i++)
    {
          
        // Add elements in first half sum
        if (i < n / 2)
        {
            sumfirst += arr[i];
        }
          
        // Add elements in the second half sum
        else
        {
            sumsecond += arr[i];
        }
    }
      
    System.out.println("Sum of first half elements is "
                                             sumfirst);
      
    System.out.println("Sum of second half elements is " +
                                            sumsecond);
}
  
// Driver code 
public static void main(String[] args) 
{
    int []arr = { 20, 30, 60, 10, 25, 15, 40 };
    int n = arr.length;
      
    // Function call
    sum_of_elements(arr, n); 
}
}
  
// This code is contributed by Princi Singh

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Python3

# Python3 program to find the sum of
# the first half elements and
# second half elements of an array

# Function to find the sum of
# the first half elements and
# second half elements of an array
def sum_of_elements(arr, n):

sumfirst = 0;
sumsecond = 0;

for i in range(n):

# Add elements in first half sum
if (i < n // 2): sumfirst += arr[i]; # Add elements in the second half sum else: sumsecond += arr[i]; print("Sum of first half elements is", sumfirst, end = "\n"); print("Sum of second half elements is", sumsecond, end = "\n"); # Driver Code arr = [20, 30, 60, 10, 25, 15, 40]; n = len(arr); # Function call sum_of_elements(arr, n); # This code is contributed # by Akanksha Rai [tabby title="C#"]

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// C# program to count pairs 
// whose sum divisible by 'K' 
using System; 
  
class GFG
    public static void sum_of_elements(int []arr, 
                                       int n)
    
          
    int sumfirst = 0, sumsecond = 0;
  
    for (int i = 0; i < n; i++)
    {
          
        // Add elements in first half sum
        if (i < n / 2)
        {
            sumfirst += arr[i];
        }
          
        // Add elements in the second half sum
        else
        {
            sumsecond += arr[i];
        }
    }
  
    Console.WriteLine("Sum of first half elements is "
                                              sumfirst);
      
    Console.WriteLine("Sum of second half elements is " +
                                              sumsecond);
}
  
// Driver code 
static public void Main () 
    int []arr = { 20, 30, 60, 10, 25, 15, 40 };
    int n = arr.Length;
      
    // Function call
    sum_of_elements(arr, n); 
  
// This code is contributed by nidhiva

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Output:

Sum of first half elements is 110
Sum of second half elements is 90

Time complexity: O(N)



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