teeNine

T9 is a system used in mobile phones with numeric keypads, that uses a predictive algorithm to help make texting faster.

Normally in order to type the word dish, you’d need to hit the 3 key once, the 4 key three times, the 7 key four times, and then the 4 key again twice. But using T9, you could just type 3, 4, 7, 4, and it’ll predict the word “dish” (or maybe “fish”, but for this challenge we won’t need to worry about that).

You need to send an urgent text, but your Nokia 3390 is out of battery so you borrow a friend’s phone. You quickly type out the text and hit send, but in your haste you forgot that the phone you’re using isn’t equipped with T9, so the text comes out all garbled.

Given a string representing the text you intend to send, return the string that you do end up sending.

Let’s assume we’re dealing with a standard mobile phone keyboard layout, where each key corresponds to a set of letters as follows:

• 2 = A,B,C
• 3 = D,E,F
• 4 = G,H,I
• 5 = J,K,L
• 6 = M,N,O
• 7 = P,Q,R,S
• 8 = T,U,V
• 9 = W,X,Y,Z

And let’s also assume that all punctuation and whitespace is handled normally.

Examples:

• For message = "cat", the output should be teeNine(message) = "bt". To spell "cat" using T9, you would press the 2 key twice, then the 8 key once, but without it two strokes of the 2 key would produce a "b".
• For message = "a cup of tea", the output should be teeNine(message) = "a atp md tda". You would enter the commands "2 287 63 832", and since each key is being pressed once at a time, it’ll produce the first letter on the key each time ("a" for 2, "t" for 8, "p" for 7, etc).
• For message = "Oh noooooo!!", the output should be teeNine(message) = "mg m!!". To spell the word "noooooo", you’d need to hit the 6 key seven times, which would cycle through the letters "m", "n", "o", "m", "n", "o", "m", settling on the final "m". Also note that the punctuation remains the same.

Input/Output:

• [execution time limit] 0.5 seconds

• [input] string message

  The text message you’re trying to type on your friend’s phone. The letters may be lowercase or uppercase. The text might also have spaces and punctuation, but those should remain unchanged in the output.

  Guaranteed constraints:
  1 ≤ message.length ≤ 160

• [output] string

  The text message you end up sending (not knowing that the phone you’re using doesn’t support T9).