You know, when the IVR says, "press 1 for menu".. etc how does it know what I pressed? Thank you for all the replies!

(Intermediate): Telephone Keypads

Telephone Keypads commonly have both digits and characters on them. This is to help with remembering & typing phone numbers (called a Phoneword), like 1-800-PROGRAM rather than 1-800-776-4726. This keypad layout is also helpful with [T9](http://en.wikipedia.org/wiki/T9_(predictive_text)), a way to type texts with word prediction.

Your goal is to mimic some of the T9-features: given a series of digits from a telephone keypad, and a list of English words, print the word or set of words that fits the starting pattern. You will be given the number of button-presses and digit, narrowing down the search-space.

Formal Inputs & Outputs

Input Description

On standard console input, you will be given an array of digits (0 to 9) and spaces. All digits will be space-delimited, unless the digits represent multiple presses of the same button (for example pressing 2 twice gives you the letter 'B').

Use the modern Telephone Keypads digit-letter layout:

0 = Not used
1 = Not used
2 = ABC
3 = DEF
4 = GHI
5 = JKL
6 = MNO
7 = PQRS
8 = TUV
9 = WXYZ

You may use any source for looking up English-language words, though this simple English-language dictionary is complete enough for the challenge.

Output Description

Print a list of all best-fitting words, meaning words that start with the word generated using the given input on a telephone keypad. You do not have to only print words of the same length as the input (e.g. even if the input is 4-digits, it's possible there are many long words that start with those 4-digits).

Sample Inputs & Outputs

Sample Input

7777 666 555 3

Sample Output

sold
solder
soldered
soldering
solders
soldier
soldiered
soldiering
soldierly
soldiers
soldiery

Challenge++

If you want an extra challenge, accomplish the same challenge but without knowing the number of times a digit is pressed. For example "7653" could mean sold, or poke, or even solenoid! You must do this efficiently with regards to Big-O complexity.

This is the best tl;dr I could make, original reduced by 94%. (I'm a bot)

> Typewriters, cash registers, and calculators Looking at the key arrangement, I was curious to learn when the system of using keys was introduced in the history of machines.

> These "Ideas" still don't provide an explanation as to why modern calculators use the reverse 9-0 arrangement.

> In 1902, the Dalton went on to become one of the most popular 10-key adding machines of the time, rendering multi-column calculators obsolete.

> From calculators to telephones Does the evolution of calculators prove its influence on modern phones? Possibly, but there's no straight answer.

> The company tested 15 layouts, using odd-shaped diagonal, pyramidal, circular and horizontal arrangements and included formats found on existing devices such as calculators and punch card machines like the IBM Model 011.

> On the other hand, Oculus Go, is adopting the calculator layout for any numeric input.

Summary Source | FAQ | Feedback | Top keywords: calculator^#1 number^#2 machine^#3 layout^#4 key^#5

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This is what i mean (Telephone keypad)

I have a project where I need the user to enter a telephone number. Thirty years ago I would have used a touchtone pad. What's a good, cheap alternative I could use today? For use with a Pro Mini if it Matters.

Pardon if this has already been attempted, my search for similar things didn't give any results.

I believe that the directions given in the images of the Summer Games video are not to be taken literally as to form a compass. I take them only to get you to think about the arrangement of something as an initial step, such as to form a box (which has already been determine by placing screenshots in the order of cardinal directions).

The key point here is D.Va. A "C" commonly thought to be "center" is not necessarily needed for a compass unless you are trying to describe relative directions, ie: "it's south of here". I don't believe the puzzle involves a series of directions, so why else would D.Va or a "center" be needed? My only conclusion is that it's to get you to 9 boxes of 3 rows/columns.

Many have thought of the number keypad on a keyboard, but that leaves out the zero, and what are you supposed to do with a number pad other than enter numbers you already posses?

A far more interesting concept to me that I've been trying to work out is using a telephone keypad. Unfortunately, it also leaves out the zero, but what it doesn't leave out is the standard alphabet assigned to numbers.

If what we're truly looking for is a password to unlock the hash, then what we could be needing is a series of digits that form a word, or a word/phrase that forms numbers.

I think I also saw at one point that it is a salted hash, and that could mean that we might also combine the numbers with the translated word or vice-verse to form the complete password.

If it's a phrase we're translating from or to, then the number "1" could be a space between words given that it does not have any assigned letters.

The only part that's providing a problem, of course, is finding an out-of-place word or set of numbers that would get me there.

If I am at work, and need to call an office that closes at 5 PM, I don't want to have to say my SSN out load. There needs to be the option to NOT use your voice.