So far, we have seen that addition is one example of a reduction operator. To perform addition as a reduction operator, we first divide the elements from our input array into groups of two, each of which is one of our subtasks. We then perform addition on each group, take the added result from each group, and divide them into groups of two again.
This process continues until we arrive at one single number. This process follows a model called binary tree reduction, which utilizes groups of two to form the subtasks:
Diagram of binary tree reduction for addition
In the preceding example with the array [1, 4, 8, 3, 2, ...
