The Polybius Square cipher is a simple substitution cipher that makes use of a 5x5 square grid. The letters A-Z are written into the grid, with "I" and "J" typically sharing a slot (as there are 26 letters and only 25 slots).
| 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|
| 1 | A | B | C | D | E |
| 2 | F | G | H | I/J | K |
| 3 | L | M | N | O | P |
| 4 | Q | R | S | T | U |
| 5 | V | W | X | Y | Z |
To encipher a message, each letter is merely replaced by its row and column numbers in the grid.
Create a function that takes a plaintext or ciphertext message, and returns the corresponding ciphertext or plaintext.
polybius("Hi") ➞ "2324"
polybius("2324 4423154215") ➞ "hi there"
polybius("543445 14343344 522433 21422415331443 52244423 4311311114") ➞ "you dont win friends with salad"
As "I" and "J" share a slot, both are enciphered into 24, but deciphered only into "I" (see third and fourth test).