Main.java

 
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
 
public class Main {
 
    protected final int TABLE_LENGTH = 30;
    protected String table[][] = new String[TABLE_LENGTH][2];
    protected int tableLength[] = new int[TABLE_LENGTH];
 
    public static void main(String[] args) throws Exception {
        Main p = new Main();
        p.run();
    }
 
    protected void run() throws Exception {
        initTable();
        while (input.ready()) {
            String line = nextLine();
            StringBuffer buf = new StringBuffer();
            int[] lengths = new int[line.length()];
            for (int i = 0; i < line.length(); i++) {
                int index = getTableIndex(line.charAt(i));
                buf.append(table[index][1]);
                lengths[i] = tableLength[index];
            }
            String morse = buf.toString();
            StringBuffer res = new StringBuffer();
            int beggin = 0;
            for (int i = line.length() - 1; i >= 0; i--) {
                res.append(getCharacter(morse.substring(beggin, beggin + lengths[i])));
                beggin += lengths[i];
            }
            System.out.println(res.toString());
        }
    }
 
    protected int getTableIndex(char match) {
        for (int i = 0; i < TABLE_LENGTH; i++) {
            if (table[i][0].charAt(0) == match) {
                return i;
            }
        }
        return 0;
    }
 
    protected String getCharacter(String match) {
        for (int i = 0; i < TABLE_LENGTH; i++) {
            if (table[i][1].equals(match)) {
                return table[i][0];
            }
        }
        return "A";
    }
 
    protected void initTable() {
        table[0][0] = "A"; table[0][1] = ".-";
        table[1][0] = "B"; table[1][1] = "-...";
        table[2][0] = "C"; table[2][1] = "-.-.";
        table[3][0] = "D"; table[3][1] = "-..";
        table[4][0] = "E"; table[4][1] = ".";
        table[5][0] = "F"; table[5][1] = "..-.";
        table[6][0] = "G"; table[6][1] = "--.";
        table[7][0] = "H"; table[7][1] = "....";
        table[8][0] = "I"; table[8][1] = "..";
        table[9][0] = "J"; table[9][1] = ".---";
        table[10][0] = "K"; table[10][1] = "-.-";
        table[11][0] = "L"; table[11][1] = ".-..";
        table[12][0] = "M"; table[12][1] = "--";
        table[13][0] = "N"; table[13][1] = "-.";
        table[14][0] = "O"; table[14][1] = "---";
        table[15][0] = "P"; table[15][1] = ".--.";
        table[16][0] = "Q"; table[16][1] = "--.-";
        table[17][0] = "R"; table[17][1] = ".-.";
        table[18][0] = "S"; table[18][1] = "...";
        table[19][0] = "T"; table[19][1] = "-";
        table[20][0] = "U"; table[20][1] = "..-";
        table[21][0] = "V"; table[21][1] = "...-";
        table[22][0] = "W"; table[22][1] = ".--";
        table[23][0] = "X"; table[23][1] = "-..-";
        table[24][0] = "Y"; table[24][1] = "-.--";
        table[25][0] = "Z"; table[25][1] = "--..";
        table[26][0] = "_"; table[26][1] = "..--";
        table[27][0] = ","; table[27][1] = ".-.-";
        table[28][0] = "."; table[28][1] = "---.";
        table[29][0] = "?"; table[29][1] = "----";
 
        for (int i = 0; i < TABLE_LENGTH; i++) {
            tableLength[i] = table[i][1].length();
        }
    }
 
    StringTokenizer st = new StringTokenizer("");
    BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
 
    public String nextToken() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(input.readLine());
        }
        return st.nextToken();
    }
 
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }
 
    public String nextLine() throws Exception {
        return input.readLine();
    }
 
}