**The reduction strategy** is a common algorithmic approach used in* parallel programming to combine the results of parallel computations into a single result*. It involves repeatedly applying a *binary operation* to pairs of elements in a data set until a single result is obtained.

In C language, the reduction strategy can be implemented using parallel programming frameworks such as OpenMP or MPI. The general steps involved in implementing a reduction using OpenMP are as follows:

- Initialize the shared variable to the identity element of the operation being performed. For example, if the operation is a summation, initialize the shared variable to zero.
- Divide the data set into equal-sized chunks and assign each chunk to a thread.
- Each thread performs the operation on its assigned chunk of the data set.
- Combine the results of each thread using the binary operation.
- Repeat steps 3 and 4 until only a single result remains.

Here’s an example of implementing the reduction strategy using **OpenMP** in C language for calculating the sum of an array of integers:

```
#include <stdio.h>
#include <omp.h>
#define ARRAY_SIZE 1000000
int main() {
int array[ARRAY_SIZE];
int i, sum = 0;
// Initialize array with values
for (i = 0; i < ARRAY_SIZE; i++) {
array[i] = i + 1;
}
#pragma omp parallel for reduction(+:sum)
for (i = 0; i < ARRAY_SIZE; i++) {
sum += array[i];
}
printf("Sum of array elements: %d\n", sum);
return 0;
}
```

In this code, we have an array of integers and we use **OpenMP** to perform the sum of the elements in parallel. The

clause specifies that the variable *reduction** sum *should be used to accumulate the result of each thread’s computation, and that the binary operation being performed is an addition (

*+*

). OpenMP automatically divides the loop iteration space among the threads and combines the results using the specified binary operation.**The reduction strategy** is a useful approach for improving the performance of parallel computations by minimizing the overhead of thread synchronization and communication.