43. Letter Combinations of a Phone Number
Given a string consisting of digits from 2 to 9 (inclusive). Return all possible letter combinations that the number can represent.
Mapping of digits to letters is given in first example.
Example 1:
Input : digits = "34"
Output : [ "dg", "dh", "di", "eg", "eh", "ei", "fg", "fh", "fi" ]
Explanation : The 3 is mapped with "def" and 4 is mapped with "ghi".
So all possible combination by replacing the digits with characters are shown in output.

Example 2:
Input : digits = "3"
Output : [ "d", "e", "f" ]
Explanation : The 3 is mapped with "def".
Now Your Turn!
Pick the correct output for the given inputInput : digits = "8"
Still unsure what the problem is asking ?
Let’s go through a few more examples, step by step, to make it clearer.
Constraints:
- 1 <= digits.length <= 4
- digts[i] contains digitd from [2,9].