int x1 = 2;
int x2 = 3;
int x3 = 4;
int x4 = 5;

int y1 = 6;
int y2 = 7;
int y3 = 8;
int y4 = 9;

int cislo = 0;

int matrix[6][6];

int moznosti[10];

int Xcursor = 0;
int Ycursor = 0;

int prosteneco = 0;
int nazev = 0;

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd1(0x27, 20, 4);
LiquidCrystal_I2C lcd2(0x28, 20, 4);

void setup() {
pinMode(x1, OUTPUT);
pinMode(x2, OUTPUT);
pinMode(x3, OUTPUT);
pinMode(x4, OUTPUT);

pinMode(y1, INPUT_PULLUP);
pinMode(y2, INPUT_PULLUP);
pinMode(y3, INPUT_PULLUP);
pinMode(y4, INPUT_PULLUP);

  lcd1.init();
  lcd2.init();

  lcd1.backlight();
  lcd2.backlight();

}

void loop() {
digitalWrite(x1, LOW);
if(digitalRead(y1) == LOW){
cislo = 1;
}
if(digitalRead(y2) == LOW){
cislo = 2;
}
if(digitalRead(y3) == LOW){
cislo = 3;
}
if(digitalRead(y4) == LOW){
Xcursor ++;
if(Xcursor > 5){
  Xcursor = 0;
  Ycursor ++;
}
if(Ycursor > 5){
  Ycursor = 0;
}
delay(250);
lcd1.clear();
lcd2.clear();

}
digitalWrite(x1, HIGH);

digitalWrite(x2, LOW);
if(digitalRead(y1) == LOW){
cislo = 4;
}
if(digitalRead(y2) == LOW){
cislo = 5;
}
if(digitalRead(y3) == LOW){
cislo = 6;
}
if(digitalRead(y4) == LOW){
 Xcursor --;
if(Xcursor < 0){
  Xcursor = 5;
  Ycursor --;
}
if(Ycursor < 0){
  Ycursor = 5;
}

delay(250);
lcd1.clear();
lcd2.clear();
}
digitalWrite(x2, HIGH);

digitalWrite(x3, LOW);
if(digitalRead(y1) == LOW){
cislo = 7;
}
if(digitalRead(y2) == LOW){
cislo = 8;
}
if(digitalRead(y3) == LOW){
cislo = 9;
}
if(digitalRead(y4) == LOW){

matrix[Xcursor][Ycursor] = cislo;

}
digitalWrite(x3, HIGH);

digitalWrite(x4, LOW);
if(digitalRead(y1) == LOW){
cislo = 13;
}
if(digitalRead(y2) == LOW){
cislo = 0;
}
if(digitalRead(y3) == LOW){
cislo = 14;
}
if(digitalRead(y4) == LOW){
SOLVING();
}
digitalWrite(x4, HIGH);

  lcd2.setCursor(19, 3);
  lcd2.print(cislo);



for(int a = 0; a < 4;a++){
  for(int i = 0; i < 6;i++){
    lcd1.setCursor(i*2, a);
    lcd1.print(matrix[i][a]);
  }
}

for(int a = 0; a < 2;a++){
  for(int i = 0; i < 6;i++){
    lcd2.setCursor(i*2, a);
    lcd2.print(matrix[i][a+4]);
  }
}

if(Ycursor < 4){
  lcd1.setCursor(Xcursor*2, Ycursor);
   lcd1.print("*");
  }else{
  lcd2.setCursor(Xcursor*2, Ycursor-4);
  lcd2.print("*");
  }
  delay(100);
}

void SOLVING(){
for(int y = 0; y < 6; y++){
  for(int x = 0; x < 6; x++){
    for(int i = 0; i < 6; i++){
      moznosti[i] = 0;
    }

if(matrix[x][y] == 0){

//-------------------------------------------------------------------------
if((x < 3) && (y < 2)){
moznosti[matrix[0][0]] = 1;
moznosti[matrix[1][0]] = 1;
moznosti[matrix[2][0]] = 1;
moznosti[matrix[0][1]] = 1;
moznosti[matrix[1][1]] = 1;
moznosti[matrix[2][1]] = 1;
}

if((x > 2) && (y < 2)){
moznosti[matrix[3][0]] = 1;
moznosti[matrix[4][0]] = 1;
moznosti[matrix[5][0]] = 1;
moznosti[matrix[3][1]] = 1;
moznosti[matrix[4][1]] = 1;
moznosti[matrix[5][1]] = 1;
}

if((x < 3) && (y < 4) && (y > 1)){
moznosti[matrix[0][2]] = 1;
moznosti[matrix[1][2]] = 1;
moznosti[matrix[2][2]] = 1;
moznosti[matrix[0][3]] = 1;
moznosti[matrix[1][3]] = 1;
moznosti[matrix[2][3]] = 1;
}

if((x > 2) && (y < 2)){
moznosti[matrix[3][2]] = 1;
moznosti[matrix[4][2]] = 1;
moznosti[matrix[5][2]] = 1;
moznosti[matrix[3][3]] = 1;
moznosti[matrix[4][3]] = 1;
moznosti[matrix[5][3]] = 1;
}

if((x < 3) && (y > 3)){
moznosti[matrix[0][4]] = 1;
moznosti[matrix[1][4]] = 1;
moznosti[matrix[2][4]] = 1;
moznosti[matrix[0][5]] = 1;
moznosti[matrix[1][5]] = 1;
moznosti[matrix[2][5]] = 1;
}

if((x > 2) && (y > 3)){
moznosti[matrix[3][4]] = 1;
moznosti[matrix[4][4]] = 1;
moznosti[matrix[5][4]] = 1;
moznosti[matrix[3][5]] = 1;
moznosti[matrix[4][5]] = 1;
moznosti[matrix[5][5]] = 1;
}

//-------------------------------------------------------------------------
for(int a = 0; a < 6; a ++){
  moznosti[matrix[a][y]] = 1;
}
for(int a = 0; a < 6; a ++){
  moznosti[matrix[x][a]] = 1;
}
//-------------------------------------------------------------------------

prosteneco = 0;
  for(int l = 1; l < 7; l++){
  if(moznosti[l] == 0){
    prosteneco ++;
    nazev = l;
  }}
  if(prosteneco == 1){
    matrix[x][y] = nazev;
  }

//------------------------------------------------------------------------

}
}
}
}