Letter Combinations of a Phone Number

Givenadigitstring,returnallpossiblelettercombinationsthatthenumbercouldrepresent.

Amappingofdigittoletters(justlikeonthetelephonebuttons)isgivenbelow.

publicclassSolution{
publicArrayList<String>letterCombinations(Stringdigits){
String[]str={"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
ArrayList<String>res=newArrayList<String>();
StringBuildersb=newStringBuilder();
DFS(digits,str,0,sb,res);
returnres;
}
publicvoidDFS(Stringdigits,String[]str,intstart,StringBuildersb,ArrayList<String>res){
if(start==digits.length()){
res.add(sb.toString());
return;
}
intd=digits.charAt(start)-'0';
for(inti=0;i<str[d].length();i++){
sb.append(str[d].charAt(i));
DFS(digits,str,start+1,sb,res);
sb.deleteCharAt(sb.length()-1);
}
}
}

ViewCode

start看成是第几个数字