Counting Elements
Explore how to implement an efficient element counting algorithm in C++17 using transform_reduce and parallel STL algorithms. Understand the process of combining transform and reduce steps to filter and count elements, and see practical examples on various containers to enhance your parallel programming skills.
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Introduction
To gain some practice, let’s build an algorithm that counts the number of elements in a container. Our algorithm will be a version of another standard algorithm count_if.
The main idea is to use transform_reduce - a new “fused” algorithm. It first applies some unary function over an element and then performs a reduce operation.
To get the count of elements that satisfy some predicate, we can firstly filter each element (transform). We return 1 if the element passes the filter and 0 ...