Given a string, you must sort the characters by occurrence (from lowest to highest).
This step is necessary to generate a Huffman tree. ( http://en.wikipedia.org/wiki/Huffman_coding )
All characters must be taken into account. Capitals are not taken into account.
If two characters appear the same number of times, the order does not matter.
You will return two arrays:
the first comprising the characters sorted. the second comprising the number of occurrence of characters of the first array.
input = 'aAabbC';
c b a
1 2 3