17. Letter Combinations of a Phone Number(bfs)

Given a string containing digits from 2-9 inclusive, 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. Note that 1 does not map to any letters.

Example:

Input: "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.

 class Solution {

     public List<String> letterCombinations(String digits) {

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

         if(digits.isEmpty()) return res;

         String[] mapping = new String[] {"0", "1", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};

         res.add("");

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

             int x=Character.getNumericValue(digits.charAt(i));

             while(res.peek().length()==i){

                 String t = res.remove();

                 for (char s :mapping[x].toCharArray())

                     res.add(t+s);

             }

         }

         return res;

     }

 }

巴特西

17. Letter Combinations of a Phone Number(bfs)

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