Print Encodings

 

public class PrintEncoding {
    public static void main(String[] args) {
        String str = "655196";
        printEncodings(str, "");
    }


    public static void printEncodings(String str, String ans) {
        if (str.length() == 0) {
            System.out.println(ans);
            return;
        }
        // left path
        int n = str.charAt(0) - '0';
        if (n == 0)
            return;
        printEncodings(str.substring(1), ans + (char) ('a' + n - 1));

        // rigth path
        if (str.length() > 1) {
            n = Integer.parseInt(str.substring(0, 2));
            if (n <= 26) {
                printEncodings(str.substring(2), ans + (char) ('a' + n - 1));
            }
        }

    }
}