package hammingdistance;

import java.io.*;
import java.util.*;
import java.math.*;

public class Main {
    public static String toBinary(int x){
        StringBuilder str = new StringBuilder("");
        for (; ;){
            if ((x & 1) == 1) str = str.append("1");
            else str = str.append("0");
            x >>= 1;
            if (x == 0) break;
        }

        StringBuilder res = new StringBuilder("");
        for (int j = 4 - str.toString().length(); j > 0; j--) res = res.append("0");
        res = res.append(str.reverse());

        return (res.toString());
    }

    public static String generate(int i){
            String str = toBinary(i);
            int p1 = (((int)str.charAt(0) + (int)str.charAt(1) + (int)str.charAt(2)) & 1) + 48;
            int p2 = (((int)str.charAt(0) + (int)str.charAt(1) + (int)str.charAt(3)) & 1) + 48;
            int p3 = (((int)str.charAt(1) + (int)str.charAt(2) + (int)str.charAt(3)) & 1) + 48;

            StringBuilder res = new StringBuilder(str);
            res = res.append((char)p1);
            res = res.append((char)p2);
            res = res.append((char)p3);

            String bin = res.toString();
            return bin;
    }

    public static int Hamming_Distance(String a, String b){
        int res = 0;
        for (int j = 0; j < 7; j++){
            if (a.charAt(j) != b.charAt(j)) res++;
        }

        return res;
    }

    public static void main(String[] args) throws Exception{
        String[] codewords = new String[16];
        for (int i = 0; i < 16; i++){
            codewords[i] = generate(i);
            //System.out.println(codewords[i]);
        }
        //codewords = new String[] {"0000000", "1110000", "1001100", "0111100", "0101010", "1011010", "1100110", "0010110", "1101001", "0011001", "0100101", "1010101", "1000011", "0110011", "0001111", "1111111"};

        final int h = 3;
        Scanner sc = new Scanner(new File("C:\\Users\\Public\\Documents\\what the hell\\data.txt"));
        PrintWriter pw = new PrintWriter(new File("C:\\Users\\Public\\Documents\\what the hell\\lol.txt"));

        int counter = 0;
        while (sc.hasNext()){
            String str = sc.nextLine();

            int len = str.length();
            StringBuilder temp = new StringBuilder("");
            for (int j = 0; j < len; j++){
                int r = (int)(Math.random() * 100);
                r = (r % 5);

                if (r == 0){
                    if (str.charAt(j) == '0') temp = temp.append('1');
                    else temp = temp.append('0');
                }
                else temp = temp.append(str.charAt(j));
            }

            String error = new String(temp);

            int c = 0;
            for (int j = 0; j < 16; j++){
                int dis = Hamming_Distance(codewords[j], error);
                if (dis < h) c++;
            }

            if (c != 1) counter++;
            if (c == 1) System.out.println("No Error");
            else System.out.println("Error!");
        }

        System.out.println(counter + "Errors Detected");
    }
}