accumulate() and partial_sum() in C++ STL : Numeric header

The accumulate() and partial_sum() are two commonly used functions from the C++ Standard Library’s <numeric> header for performing operations on sequences of values, typically in a container like a vector or an array.

1. accumulate() Function:
   std::accumulate() computes the sum of all the elements in a range.

 #include <iostream>
 #include <vector>
 #include <numeric>

 int main() {
     std::vector<int> numbers = {1, 2, 3, 4, 5};
     int sum = std::accumulate(numbers.begin(), numbers.end(), 0);

     std::cout << "Sum of elements: " << sum << std::endl;
     return 0;
 }

In this example, std::accumulate() adds up all the values in the numbers vector, starting with an initial value of 0.

2. partial_sum() Function:
   std::partial_sum() computes the partial sums of the elements in a range and stores them in another range or container.

 #include <iostream>
 #include <vector>
 #include <numeric>

 int main() {
     std::vector<int> numbers = {1, 2, 3, 4, 5};
     std::vector<int> partial_sums(numbers.size());

     std::partial_sum(numbers.begin(), numbers.end(), partial_sums.begin());

     std::cout << "Partial Sums: ";
     for (const int& num : partial_sums) {
         std::cout << num << " ";
     }
     std::cout << std::endl;

     return 0;
 }

In this example, std::partial_sum() calculates and stores the partial sums in the partial_sums vector. The output will be “Partial Sums: 1 3 6 10 15,” which are the cumulative sums of the original vector.

Both accumulate() and partial_sum() are powerful tools for performing operations on sequences of values, and they can be customized with different binary operators and initial values to perform various calculations beyond simple addition.