import java.util.Scanner; 

public class SymmetricEncryption 
{ 
    private static int[] count = new int[20]; 
    private static char [] charAr = new char[20]; 
    private static int k = 0; 
    private static String all = "!abcdefghijklmnopqrstuvwxyz"; 
    private static String code = "etaoinshrd"; 
    private static int cell = 0; 

    public static String shiftVal (String s, int shift) 
    { 
        char[] input = s.toCharArray(); 
        for (int i = 0; i <input.length; i++) 
        { 
            if (input[i] != ' ') 
            { 
                int loc = all.indexOf(input[i]) + shift; 

                if (loc <= 0) 
                { 
                    loc = 26 + loc; 
                } 
                else if (loc > 26) 
                { 
                    loc = loc - 26; 

                } 
                input[i] = all.charAt(loc); 
            } 
        } 
        String answer = String.valueOf (input); 
        return answer; 
    } 

    public static char nextMax () 
    { 
        int max = -100; 
        char maxVal= ' '; 
        for (int i = 0; i <charAr.length; i++) 
        { 
            if (count[i] > max) 
            { 
                max = count[i]; 
                cell = i; 
                maxVal = charAr[i]; 
            } 
        } 
        return maxVal; 
    } 

    public static String enryptLine (String s, int shift) 
    { 
        char[] input = s.toCharArray(); 
        for (int i = 0; i <input.length; i++) 
        { 
            if (input[i] != ' ') 
            { 
                int loc = shift + all.indexOf(input[i]); 

                if (loc > 26) 
                { 
                    loc = (loc - 26); 
                } 
                input[i] = all.charAt(loc); 

            } 
        } 
        String answer = String.valueOf (input); 
        return answer; 
    } 

    public static void freqCount (String line) 
    { 
        for (int i = 0; i <line.length(); i++) 
        { 
            boolean flag = false; 
            int cell = 0; 
            if (line.charAt(i) != ' ') 
            { 
                for (int j = 0; j <charAr.length; j++) 
                { 
                    if (line.charAt(i) == charAr[j]) 
                    { 
                        flag = true; 
                        cell = j; 
                    } 
                } 
                if (flag == false) 
                { 
                    charAr[k] = line.charAt(i); 
                    count[k]++; 
                    k++; 
                } 
                else 
                { 
                    count[cell]++; 
                } 
            } 
        } 
    } 

    public static boolean allDone() 
    { 
        int counting = 0; 
        for (int i = 0; i<20; i++) 
        { 
            if (count[i] == 0) 
            { 
                counting++; 
            } 
        } 
        if (counting == 20) 
        { 
            return true; 
        } 
        else 
        { 
            return false; 
        } 
    } 

    public static void main (String args[]) 
    { 
        System.out.println ("Decrypt"); 
        Scanner scanner = new Scanner (System.in); 

        System.out.println("Input the sentence to be decoded - Only alphabets and spaces and lower case"); 
        String Line = scanner.nextLine(); 

        System.out.println("Input shift value - 1, 2.....26"); 
        int value = scanner.nextInt(); 

        String answer = enryptLine (Line, value); 
        System.out.println ("Encrypted Text = " + answer); 

        System.out.println ("\n\n"); 

        String line = answer; 
        boolean flag2 = false; 
        int counter = 0, tries = 0; 

        while (flag2 == false) 
        { 
            freqCount (line); 
            boolean flag = false; 
            System.out.println ("Checking with the letter : " + code.charAt(counter)); 
            System.out.println ("\n\n"); 

            while (flag == false && allDone() == false) 
            { 
                tries++; 
                int move = code.charAt(counter) - nextMax(); 
                String newVal = shiftVal (line, move); 
                if (newVal.equals(Line)) 
                { 
                    System.out.println ("Try#" + tries + " Decrypted Text Guess = " + newVal); 
                    System.out.println ("Accurate!"); 
                    System.out.println ("\n\n"); 
                    flag = true; 
                } 
                else 
                { 
                    System.out.println ("Tryl#" + tries + " Decrypted Text Guess = " + newVal); 
                    System.out.println ("Incorrect - Trying the nextmost common letter"); 
                    count[cell] = 0; 
                    System.out.println ("\n\n"); 
                } 
            } 
            if (flag == true) 
            { 
                System.out.println ("Text Decrypted in " + tries + " trials"); 
                flag2 = true; 
            } 
            else 
            { 
                counter++; 
            } 
        } 
    } 
}