Find dictionary words matching a phone digit string

You are given:

• A digit string digits consisting of characters '2' – '9' .
• A list of lowercase words words (dictionary).

Use the classic phone keypad mapping:

• 2 -> abc , 3 -> def , 4 -> ghi , 5 -> jkl ,
• 6 -> mno , 7 -> pqrs , 8 -> tuv , 9 -> wxyz

A word matches digits if:

• The word length equals len(digits) , and
• For every position i , the i -th character of the word is one of the letters mapped from digits[i] .

Return all words from words that match digits.

Input / Output

• Input: digits: string , words: list[string]
• Output: list[string] containing all matching words (any order is acceptable).

Constraints (reasonable interview assumptions)

• 1 <= len(digits) <= 20
• 0 <= len(words) <= 2 * 10^5
• Each word contains only a – z and has length up to 20.

Examples

• digits = "8733" , words = ["tree", "used", "free", "true"] → output could be ["tree", "used"] .