Phone number letters
Mediumbacktrackingstringhash map
As on old phone keypads: 2=abc, 3=def, 4=ghi, 5=jkl, 6=mno, 7=pqrs, 8=tuv, 9=wxyz. Return every string digits could type. Return [] for empty digits. Order doesn't matter.
Example 1
Input: digits = "23" Output: ["ad","ae","af","bd","be","bf","cd","ce","cf"]
Example 2
Input: digits = "" Output: []
Constraints
- 0 ≤ digits.length ≤ 4
- digits[i] is 2–9
Submit checks your solution against 7 tests, including hidden ones.
/**
* @param {string} digits
* @return {string[]}
*/
function letterCombinations(digits) {
}