[Leedcode 17] Letter combinations of a Phone number

 Public classSolution { PublicList<string>Res;  PublicStringBuilder seq;  PublicList<string>lettercombinations (String digits) {//The subject is similar to a fully arranged variant, and each optional value of the entire arrangement needs to be taken out according to the incoming number corresponding//DFS idea. Recursion in the loop, recursive function requires a parameter level, indicating the number of recursive bitsres=NewArraylist<string>(); Seq=NewStringBuilder (); if(Digits.length () ==0)returnRes; String[] Trans={"", "", "abc", "Def", "Ghi", "JKL", "MnO", "PQRS", "TUV", "WXYZ"}; getlettercom (digits,0, trans); returnRes; }     Public voidGetlettercom (String digits,intlevel,string trans[]) {        if(level==digits.length ())            {Res.add (seq.tostring ()); return; }        intN=digits.charat (level)-' 0 '; String Temp=Trans[n];  for(intI=0;i<temp.length (); i++) {seq.append (Temp.charat (i)); Getlettercom (Digits,level+1, trans);        Seq.deletecharat (level); }                    }}

[Leedcode 17] Letter combinations of a Phone number