# Sum of the first M elements of Array formed by infinitely concatenating given array

Given an array **arr[]** consisting of **N** integers and a positive integer **M**, the task is to find the sum of the first **M** elements of the array formed by the infinite concatenation of the given array **arr[]**.

**Examples:**

Input:arr[] = {1, 2, 3}, M = 5Output:9Explanation:

The array formed by the infinite concatenation of the given array arr[] is of the form {1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, … }.

The sum of the first M(= 5) elements of the array is 1 + 2 + 3 + 1 + 2 = 9.

Input:arr[] = {1}, M = 7Output:7

**Approach:** The given problem can be solved by using the** Modulo Operator (%)**** **and consider the given array as the circular array and find the sum of the first **M** elements accordingly. Follow the steps below to solve this problem:

- Initialize a variable, say
**sum**as**0**to store the resultant sum of the first**M**elements of the new array. - Iterate over the range
**[0, M – 1]**using the variable**i**and increment the value of**sum**by**arr[i%N]**. - After completing the above steps, print the value of the
**sum**as the result.

Below is the implementation of the above approach:

## C++

`// C++ program for the above approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to find the sum of first` `// M numbers formed by the infinite` `// concatenation of the array A[]` `int` `sumOfFirstM(` `int` `A[], ` `int` `N, ` `int` `M)` `{` ` ` `// Stores the resultant sum` ` ` `int` `sum = 0;` ` ` `// Iterate over the range [0, M - 1]` ` ` `for` `(` `int` `i = 0; i < M; i++) {` ` ` `// Add the value A[i%N] to sum` ` ` `sum = sum + A[i % N];` ` ` `}` ` ` `// Return the resultant sum` ` ` `return` `sum;` `}` `// Driver Code` `int` `main()` `{` ` ` `int` `arr[] = { 1, 2, 3 };` ` ` `int` `M = 5;` ` ` `int` `N = ` `sizeof` `(arr) / ` `sizeof` `(arr[0]);` ` ` `cout << sumOfFirstM(arr, N, M);` ` ` `return` `0;` `}` |

## Java

`// Java program for the above approach` `import` `java.io.*;` `import` `java.lang.*;` `class` `GFG {` ` ` `// Function to find the sum of first` ` ` `// M numbers formed by the infinite` ` ` `// concatenation of the array A[]` ` ` `public` `static` `int` `sumOfFirstM(` `int` `A[], ` `int` `N, ` `int` `M)` ` ` `{` ` ` ` ` `// Stores the resultant sum` ` ` `int` `sum = ` `0` `;` ` ` `// Iterate over the range [0, M - 1]` ` ` `for` `(` `int` `i = ` `0` `; i < M; i++) {` ` ` `// Add the value A[i%N] to sum` ` ` `sum = sum + A[i % N];` ` ` `}` ` ` `// Return the resultant sum` ` ` `return` `sum;` ` ` `}` ` ` `// Driver Code` ` ` `public` `static` `void` `main(String[] args) {` ` ` `int` `arr[] = { ` `1` `, ` `2` `, ` `3` `};` ` ` `int` `M = ` `5` `;` ` ` `int` `N = arr.length;` ` ` `System.out.println(sumOfFirstM(arr, N, M));` ` ` `}` `}` `// This code is contributed by gfgking.` |

## Python3

`# Python3 program for the above approach` `# Function to find the sum of first` `# M numbers formed by the infinite` `# concatenation of the array A[]` `def` `sumOfFirstM(A, N, M):` ` ` ` ` `# Stores the resultant sum` ` ` `sum` `=` `0` ` ` `# Iterate over the range [0, M - 1]` ` ` `for` `i ` `in` `range` `(M):` ` ` ` ` `# Add the value A[i%N] to sum` ` ` `sum` `=` `sum` `+` `A[i ` `%` `N]` ` ` `# Return the resultant sum` ` ` `return` `sum` `# Driver Code` `if` `__name__ ` `=` `=` `'__main__'` `:` ` ` ` ` `arr ` `=` `[ ` `1` `, ` `2` `, ` `3` `]` ` ` `M ` `=` `5` ` ` `N ` `=` `len` `(arr)` ` ` ` ` `print` `(sumOfFirstM(arr, N, M))` ` ` `# This code is contributed by ipg2016107` |

## C#

`// C# program for the above approach` `using` `System;` `class` `GFG {` ` ` `// Function to find the sum of first` ` ` `// M numbers formed by the infinite` ` ` `// concatenation of the array A[]` ` ` `static` `int` `sumOfFirstM(` `int` `[] A, ` `int` `N, ` `int` `M)` ` ` `{` ` ` `// Stores the resultant sum` ` ` `int` `sum = 0;` ` ` `// Iterate over the range [0, M - 1]` ` ` `for` `(` `int` `i = 0; i < M; i++) {` ` ` `// Add the value A[i%N] to sum` ` ` `sum = sum + A[i % N];` ` ` `}` ` ` `// Return the resultant sum` ` ` `return` `sum;` ` ` `}` ` ` `// Driver Code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `int` `[] arr = { 1, 2, 3 };` ` ` `int` `M = 5;` ` ` `int` `N = arr.Length;` ` ` `Console.WriteLine(sumOfFirstM(arr, N, M));` ` ` `}` `}` `// This code is contributed by subhammahato348.` |

## Javascript

`<script>` ` ` ` ` `// JavaScript program for the above approach` ` ` `// Function to find the sum of first` ` ` `// M numbers formed by the infinite` ` ` `// concatenation of the array A[]` ` ` `function` `sumOfFirstM(A, N, M) {` ` ` `// Stores the resultant sum` ` ` `let sum = 0;` ` ` `// Iterate over the range [0, M - 1]` ` ` `for` `(let i = 0; i < M; i++) {` ` ` `// Add the value A[i%N] to sum` ` ` `sum = sum + A[i % N];` ` ` `}` ` ` `// Return the resultant sum` ` ` `return` `sum;` ` ` `}` ` ` `// Driver Code` ` ` `let arr = [1, 2, 3];` ` ` `let M = 5;` ` ` `let N = arr.length;` ` ` `document.write(sumOfFirstM(arr, N, M));` ` ` `// This code is contributed by Potta Lokesh` ` ` `</script>` |

**Output:**

9

**Time Complexity:** O(M)**Auxiliary Space:** O(1)

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