Build optimal prefix code for given string consisted of a-z letters. One the
first line output k n, where k -- number of distinct letters, n -- length
of encoded string. Next k lines should containt letter: code. On the last
line output encoded string.
Sample Input:
abacabad
Sample Output:
4 14
a: 0
b: 10
c: 110
d: 111
01001100100111
The original problem was taken form: https://stepik.org/lesson/13239/step/5?unit=3425
Job make gen will generate tests inputs for Huffman encoding and Huffman decoding problems.