# Simple Solution beats 39% using Delimiter and Backtracking

• Hi I have solved this question using delimiter.
There are two types of numbers like
3 digit: 3 ("abc"), 4 ("def")
4 digit: 7 ("pqrs"), 9 ("wxyz")

So i have appended delimiter "Z" to 3 digit numbers . so as to convert those 3 digit to 4 digits.

``````       public List<String> letterCombinations(String inp) {

String s[]={"abcZ","defZ","ghiZ","jklZ","mnoZ","pqrs","tuvZ","wxyz"};
List <String> row= new ArrayList<String>();
String temp="";
if(inp.length()==0)
return row;
letterComibinations1(inp,s,row,temp,0);
return row;
}

public void letterComibinations1(String inp, String s[], List<String> row, String temp,int j){
if(j==inp.length())
return;
}

for(int i=0;i<4;i++)
{

if(s[Character.getNumericValue(inp.charAt(j))-2].charAt(i)=='Z')continue;
temp+= s[Character.getNumericValue(inp.charAt(j))-2].charAt(i);
letterComibinations1(inp,s,row,temp,j+1);
temp=temp.substring(0,temp.length()-1);

}
}
``````

}

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