# Generate all possible Letter combinations from numbers.

• If a=1, b=2, c=3,....z=26. Given a string, find all possible codes that string can generate. Give a count as well as print the strings.

For example:
Input: "1123". You need to general all valid alphabet codes from this string.

Output List
aabc //a = 1, a = 1, b = 2, c = 3
kbc // since k is 11, b = 2, c= 3
alc // a = 1, l = 12, c = 3
aaw // a= 1, a =1, w= 23
kw // k = 11, w = 23

• I tried this today. Here is the basic code that was tested only on this example:

``````
public static void possibleCodes(String input, String s,
List<String> list)
{
if (input.isEmpty())
{
return;
}
for (int i = 1; i <= 2; i++)
{
if (input.length() >= i)
{
String sub = input.substring(0, i);// 1
int val = Integer.valueOf(sub);
if (val > 26)
{
continue;
}
possibleCodes(input.substring(i), s + numToChar(sub), list);
}
}
}

private static String numToChar(String s)
{
Integer i = Integer.valueOf(s);
StringBuilder builder = new StringBuilder();
builder.append((char) ('a' - 1 + i));
return builder.toString();
}
``````

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