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.
Brute force method can be accepted by leetcode online judge.
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public
class
Solution {
public
ArrayList<String> letterCombinations(String digits) {
String[] keyboard = new
String[]{"","","abc","def","ghi","jkl","mno",
"pqrs","tuv","wxyz"};
ArrayList<String> result = new
ArrayList<String>();
result.add("");
for(int
i = 0; i < digits.length(); ++i){
int
k = digits.charAt(i) - 48;
if(k != 0
&& k != 1){
ArrayList<String> temp = new
ArrayList<String>();
while(!result.isEmpty()){
String s = result.remove(0);
for(int
j = 0; j < keyboard[k].length(); ++j){
StringBuffer stb = new
StringBuffer(s);
stb.append(keyboard[k].charAt(j));
temp.add(stb.toString());
}
}
result = temp;
}
}
return
result;
}
} |