Letter Combinations of a Phone Number
Detailed guide and Python implementation for the 'Letter Combinations of a Phone Number' problem.
Problem Statement
Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.
A mapping of digits to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.
2: abc, 3: def, 4: ghi, 5: jkl, 6: mno, 7: pqrs, 8: tuv, 9: wxyz
Implement a function letterCombinations(digits: str) -> list.
- •0 <= digits.length <= 4
- •digits[i] is a digit in the range ['2', '9']
Examples
"23"
["ad","ae","af","bd","be","bf","cd","ce","cf"]
Digit 2 maps to 'abc' and digit 3 maps to 'def'. All combinations of one letter from each digit are generated.
""
[]
Empty input produces no combinations.
"2"
["a","b","c"]
Digit 2 maps to 'abc'.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
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