FilesExpand file tree

 master

/

LetterCombinationsofaPhoneNumber.java

Copy path

BlameMore file actions

BlameMore file actions

Latest commit

 

History

History

History

35 lines (33 loc) · 1.35 KB

 master

/

LetterCombinationsofaPhoneNumber.java

Top

File metadata and controls

• Code
• Blame

35 lines (33 loc) · 1.35 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

/*

Author: King, wangjingui@outlook.com

Date: Dec 20, 2014

Problem: Letter Combinations of a Phone Number

Difficulty: Medium

Source: https://oj.leetcode.com/problems/letter-combinations-of-a-phone-number/

Notes:

Given a digit string, return all possible letter combinations that the number could represent.

A mapping of digit to letters (just like on the telephone buttons) is given below.

Input:Digit string "23"

Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].

Note:

Although the above answer is in lexicographical order, your answer could be in any order you want.

Solution: ...

*/

public class Solution {

public List<String> letterCombinations(String digits) {

ArrayList<String> res = new ArrayList<String>();

String[] keyboard = new String[]{" ","","abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};

letterCombinationsRe(keyboard,res,digits,"");

return res;

}

public void letterCombinationsRe(String[] keyboard, ArrayList<String> res, String digits, String s) {

if (s.length() == digits.length()) {

res.add(s);

return;

}

String letters = keyboard[digits.charAt(s.length()) - '0'];

for (int i = 0; i < letters.length(); ++i) {

letterCombinationsRe(keyboard, res, digits, s+letters.charAt(i));

}

}

}