import "util.scrypt";
import "array.scrypt";

contract Sudoku {

 bytes board;

 static const int N = 9;
 static bytes EMPTY = b'00';

 constructor(bytes board) {
  this.board = board;
 }

 function merge(bytes solution) : bytes {
  bytes newBoard = this.board;
  int i = 0;
  loop (N) {
   int j = 0;
   loop (N) {

    int value = this.readValue(newBoard, i, j);
    int inputValue = this.readValue(solution, i, j);
    if (value == 0) {
     require(inputValue <= 9);
     newBoard = this.setValue(newBoard, i, j, inputValue);
    } else {
     require(value == inputValue);
    }
    j++;
   }

   i++;
  }
  return newBoard;
 }

 public function solve(bytes solution) {

  require(len(solution) == Sudoku.N * Sudoku.N);

  bytes newBord = this.merge(solution);

  Array rowArray = new Array();
  Array colArray = new Array();
  Array squareArray = new Array();

  int i = 0;
  loop (N) {
   int j = 0;

   loop (N) {
    // check for duplicate

    // in a row
    int rowElem = this.readValue(newBord, i, j);
    require(rowArray.indexOf(rowElem) == -1);
    rowArray.push(rowElem);

    // in a column
    int colElem = this.readValue(newBord, j, i);
    require(colArray.indexOf(colElem) == -1);
    colArray.push(colElem);

    // in a subgrid
    int squareElem = this.readSquareValue(newBord, i, j);
    require(squareArray.indexOf(squareElem) == -1);
    squareArray.push(squareElem);

    j++;
   }

   rowArray.clear();
   colArray.clear();
   squareArray.clear();

   i++;
  }

  require(true);
 }

 static function readValue(bytes board, int i, int j): int {
  return Util.fromLEUnsigned(Util.getElemAt(board, Sudoku.index(i, j)));
 }

 static function setValue(bytes board, int i, int j, int value): bytes {
  return Util.setElemAt(board, this.index(i, j), Util.toLEUnsigned(value, 1));
 }

 static function readSquareValue(bytes board, int i, int j): int {
  return Util.fromLEUnsigned(Util.getElemAt(board, Sudoku.indexSquare(i, j)));
 }


 static function index(int row, int col) : int {
  return row * Sudoku.N + col;
 }

 static function indexSquare(int i, int j) : int {
  int row = i / 3 * 3 + j / 3;
  int col = i % 3 * 3 + j % 3;
  return Sudoku.index(row, col);
 }
}