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What letters go with phone numbers?
The letters have also been used, mainly in the United States, as a technique for remembering telephone numbers easily. For example, an interior decorator might license the telephone number 1-800-724-6837, but advertise it as the more memorable phoneword 1-800-PAINTER….Layout.
| Number | Letter |
|---|---|
| 2 | ABC |
| 3 | DEF |
| 4 | GHI |
| 5 | JKL |
What does letters in a phone number mean?
These were the hubs through which an area’s calls would be routed. Phone subscribers were given a unique five-digit number within their service area. These would be preceded by two digits—which were identified by letters—that denoted the telephone exchange you were connected to.
How to find all possible letter combinations of a phone number?
17. Letter Combinations of a Phone Number 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.
How to return all possible letter combinations in leetcode?
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 digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.
How to write a solution for letter combinations?
Using the backtracking method, the solution is very simple. The solution is based on the fact that; if the length of the letter combination is equal to the length of the digits, we shall write it in our final result set.
How to check the next digits of a phone number?
Iterate over the letters mapping the next available digit. Append the current letter to the current combination combination = combination + letter. Proceed to check the next digits : recurse (combination + letter, next_digits [1:]).