Rolling Encryption

Points: 10

Time limit: 1.0s

Memory limit: 64M

Problem type

You have a sequence of lowercase characters that you want to encrypt.

The first $k$ ~k~ characters will be encoded as plain-text. All characters after the first $k$ ~k~ characters will be shifted by the most frequently occurring character that appeared in the previous $k$ ~k~ characters, with ties broken by the character which occurs first in the alphabet.

By "shifted by", we mean that if c was the most frequently occurring character, the character would be shifted ahead by $3$ ~3~ positions (since c is the third letter of the alphabet), modulo $26$ ~26~ (e.g., b becomes e, and z becomes c).

Input Specification

The first line of input contains $k$ ~k~ $(1 \le k \le 10\,000)$ ~(1 \le k \le 10\,000)~. The next line contains $c$ ~c~ characters $(1 \le c \le 100\,000)$ ~(1 \le c \le 100\,000)~.

Output Specification

One line, containing the encrypted version of the $c$ ~c~ characters from the input.

Sample Input

5
abbaabbacdecde

Output for Sample Input

abbaacdcdegdgh

Troy Vasiga

Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported

Comments

-1

SKTSnaker commented on Feb. 26, 2017, 10:07 p.m.

I think the sample output may be incorrect.

Take the third last character (c) and the previous 5 characters(bacde) The shift with b should be 2 instead of 1.

Therefore shouldn't d be e?

0

Phoenix1369 commented on Feb. 26, 2017, 10:33 p.m.

ties broken by the character which occurs first in the alphabet.

2

bobhob314 commented on June 26, 2015, 2:27 p.m. ← edit 7 →

Helpful Notice

By

the previous $k$ ~k~ characters,

Mr. Vasiga means in the original, unaltered string.