Suppose our input data to a map-reduce operation consists of integer values
(the keys are not important). The map function takes an integer
i
and produces the list of pairs (
p,
i) such that
p is a
prime divisor of
i. For example, map(12) = [(2,12), (3,12)].
The reduce function is addition. That is,
reduce(p, [i1, i2, ...,ik])
is (p,i1+i2+...+ik).
Compute the output, if the input is the set of integers 15, 21, 24, 30, 49.
Then, identify, in the list below, one of the pairs in the output.