21 Match Sticks Game

21 Match Sticks is a small game. That can be implemented easily in any programming language.

In this game, user/computer needs to pick 1 to 4 sticks and whoever picks the last stick will lose the game.

import java.util.Scanner;

public class MatchSticks21 {

      public static void main(String[] args) {

            int matchstick = 21;

            int user = 0;

            int computer = 0;

            Scanner scanner = new Scanner(System.in);

            while (matchstick >= 1) {

                  if (matchstick == 1) {

                        System.out.println("Match stick status: " + matchstick);

                        System.out.println("\nYou loose!!!!!!:(:(");

                        break;

                  }                            

                  System.out.println("Match stick status: " + matchstick);

                  System.out.println("\nEnter the choice (1,2,3,4)):");

                  user = scanner.nextInt();

                  System.out.println("\nYou picked: " + user);

                  if (user >= 5 || user <= 0) {

                        System.out.println("\nInvalid value");

                        continue;

                  }

                  computer = 5 - user;

                  System.out.println("\nComputer picked " + computer);

                  matchstick = matchstick - computer - user;

            }

      }

}

Solving Sudoku in Simpler Way

Here, I have presented simple logic to solve sudoku with simple methods.

public class MySudoku {

      public static void main(String[] args) {

            new MySudoku(new int[9][9]).display();

      }

      private final int[][] sudoku;

      public MySudoku(int[][] sudoku) {

            this.sudoku = sudoku;

            solve(0, 0);

      }

      public boolean checkColumn(int row, int value) {

            for (int column = 0; column < 9; column++) {

                  if (sudoku[row][column] == value) {

                        return false;

                  }

            }

            return true;

      }

      public boolean checkRow(int column, int value) {

            for (int row = 0; row < 9; row++) {

                  if (sudoku[row][column] == value) {

                        return false;

                  }

            }

            return true;

      }

      public boolean checkBox(int row, int column, int value) {

            int boxRow = (row / 3) * 3;

            int boxColumn = (column / 3) * 3;

            for (int aRow = 0; aRow < 3; aRow++) {

                  for (int aColumn = 0; aColumn < 3; aColumn++) {

                        if (sudoku[boxRow + aRow][boxColumn + aColumn] == value) {

                              return false;

                        }

                  }

            }

            return true;

      }

      public boolean solve(int row, int column) {

            if (row == 9) {

                  row = 0;

                  column = column + 1;

                  if (column == 9) {

                        return true;

                  }

            }

            if (sudoku[row][column] != 0) {

                  return solve(row + 1, column);

            }

            for (int value = 1; value <= 9; value++) {

                  if (checkBox(row, column, value)

                              && checkColumn(row, value)

                              && checkRow(column, value)) {

                        sudoku[row][column] = value;

                        if (solve(row + 1, column)) {

                              return true;

                        }

                  }

            }

            sudoku[row][column] = 0;

            return false;

      }

      public void display() {

            for (int row = 0; row < 9; row++) {

                  System.out.println();

                  for (int column = 0; column < 9; column++) {

                        System.out.print("\t" + String.valueOf(sudoku[row][column]));

                  }

                  System.out.println();

            }

      }

}