By utilizing the accumulate function in C++, we can efficiently calculate the sum of an array.
A sequential data structure known as an array stores elements of the same data type consecutively in a contiguous block of memory.
The total of all elements within an array is referred to as the array sum.
There exist multiple methods in the C++ programming language for calculating the sum of an array.
// C++ program to demonstrate working of accumulate()
#include <iostream>
#include <numeric>
using namespace std;
// User defined function that returns sum of
// arr[] using accumulate() library function.
int arraySum(int a[], int n)
{
int initial_sum = 0;
return accumulate(a, a+n, initial_sum);
}
int main()
{
int a[] = {5 , 10 , 15} ;
int n = sizeof(a)/sizeof(a[0]);
cout << arraySum(a, n);
return 0;
}
Output:
Time Complexity: O(n)
Space Complexity: O(n) denoting the array's size as 'n'.
Sum of vector
// C++ program to demonstrate working of accumulate()
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
// User defined function that returns sum of
// arr[] using accumulate() library function.
int arraySum(vector<int> &v)
{
int initial_sum = 0;
return accumulate(v.begin(), v.end(), initial_sum);
}
int main()
{
vector<int> v{5 , 10 , 15} ;
cout << arraySum(v);
return 0;
}
Output:
Time Complexity: O(n)
Space Complexity: O(n) denotes that the amount of space required by the algorithm grows linearly with the size of the array, represented by 'n'.
Classical technique
A straightforward method to compute the total of an array's elements involves iterating through each element and incrementing the sum variable by the element's value.
Algorithm
Step 1 : For i from 0 to n-1, follow step 2 ;
Step 2 : sum = sum + arr[i]
Step 3 : print sum.
Example
Live Demo
#include <iostream>
using namespace std;
int main (){
int arr[] = { 2, 5, 7, 8, 2, 6, 9 };
int n = 7, sum = 0;
for(int i = 0; i<n ; i++){
sum+=arr[i];
}
cout<<"The array sum is "<<sum;
return 0;
}
Output:
The array sum is 39
Using Accumulate Method
The accumulate function in C++ is employed to calculate the total of elements in an array. This functionality is accessible within the numeric library in C++. To utilize this function, the code must include the numeric> header file at the start, as it houses the implementation for the accumulate function:
Syntax
accumulate(array_name , array_name+length , sum);
Example
Live Demo
#include <iostream>
#include <numeric>
using namespace std;
int main (){
int arr[] = { 2, 5, 7, 8, 2, 6, 9 };
int n = 7, sum = 0;
sum = accumulate(arr, arr+n, sum);
cout<<"The array sum is "<<sum;
return 0;
}
Output:
The array sum is 39
Using Sum Of Vectors
You can also apply the accumulate function to vectors. This function will provide the total sum of the array represented in vector form.
Example
Live Demo
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
int arraySum(vector<int> &v){
int initial_sum = 0;
return accumulate(v.begin(), v.end(), initial_sum);
}
int main(){
vector<int> v{12, 56, 76, 2, 90 , 3} ;
int sum = 0;
sum=accumulate(v.begin(), v.end(), sum);
cout<<"The sum of array is "<<sum;
return 0;
}
Output:
The sum of array is 239
Use a for loop
We can employ a for loop to iterate through the array. Each element can be accumulated sequentially:
Initialize sum = 0.
Run a for loop from i = 0 to i = size - 1.
At each iteration of the for loop, calculate the sum by adding the current array element, such as sum = sum + arr[i].
Upon completion of the for loop, the cumulative total of all elements will be saved in the sum variable.
#include <iostream>
using namespace std;
int main() {
// initialise array
int arr[] = {2, 4, 6, 8};
int size = 4;
// initialise sum to zero
int sum = 0;
// for loop runs from 0 to size - 1
for(int i = 0; i < size; i++)
{
sum = sum + arr[i];
}
cout << "The sum of the elements in the array: " << sum;
}
Output:
The sum of the elements in the array: 20
Using valarray sum function
By calling the sum member function of the valarray class, which serves as a replacement for the traditional array, you can execute the sum operation directly on the valarray object.
