java and aws expert for median-string-based Motif search algorithm Map & Reduce

The most vital thing in applying the MapReduce framework to real-world problems is to
identify what the keys and values are. While there are more advanced approaches, the following
hint is a naïve method for inspiring your creativity.

You can use the candidate median strings (of a total of 65536) as the keys, and the total matching
distances of the respective candidates as the values. That means you will not get the keys from
input but generate the keys (i.e., enumerating the candidate median strings) through your code on
the fly. Your Map function outputs each median string paired with its total matching distance;
your Reduce function reverses each key/value pair such as <k,v>  <v,k>. The output of Reduce
will be a sorted list of the reversed pairs and the first pair has the minimum total matching
distance and the motif you have found.