KeypadKata

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, 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.

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.

You can download the dictionary from the repo

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 task but without knowing the number of times a digit is pressed. For example "7653" could mean sold, or poke, or even solenoid!

Think about efficient code with regards to Big-O complexity

Challenge+++

The predicted words have to be sorted by the priority comes from user interactions. If a user picks one word from the predicted ones, the next time it will be the first in the list. Every time the user chooses one word, its priority became stronger.

Sample interaction and output predictions

sold solder soldered soldering

Choosing soldered:

soldered sold solder soldering

Choosing solder three times:

solder soldered sold soldering