queen.java

用java实现的八皇后

//The class to represent the 8*8 chessboard
class chessboard{
	
	int [][]board = new int[8][8];
	int printCount = 0;
	
	//Initialization
	chessboard(){
		for(int i = 0; i < 8 ; i++)
			for(int j = 0; j < 8 ; j++)
				board[i][j] = 0;
	}
	
	//Put down a chess
	public void putDown(int x,int y){
		board[x][y] = 1;
	}
	
	//Show the chessboard
	public void show(){
		printCount++;
		String out = "No.";
		out += printCount;
		out += " solution:";
		out += '\n';
		System.out.print(out);
		for(int i = 0; i < 8 ; i++){
			for(int j = 0;j < 8 ; j++){
				if(board[i][j] == 1)
					System.out.print('O');
				else
					System.out.print('X');
				System.out.print(' ');
			}
			System.out.print('\n');
		}
		System.out.print('\n');
	}
	
	//Judge whether it is eligible for the game
	public boolean check(int i,int j){
		for (int x = 0;  x < 8;  x ++) {
			if (i == x) continue;
			if (board[x][j] == 1) return false;
			int k = j - (i - x);
			if ((k >= 0) && (k <= 7) && (board[x][k] == 1)) return false;
			k = j + (i - x);
			if ((k >= 0) && (k <= 7) && (board[x][k] == 1)) return false;
		}
		return true;
	}
	
	//Try to put a chess
	public void put(int n){
		int i;
		i = 0;
		for (;  i < 8;  i++) {
			if (check(n, i)) {
				putDown(n, i);
				if (n == 7) {
					show();
				}
				else 
					put(n + 1);
				board[n][i] = 0;
			}
		}
	}
	
	//Show the number of arrangements
	public int showCount(){
		return printCount;
	}
	
	
}
public class Queen {
	
	static chessboard cb = new chessboard();
	
	
	public static void main(String[] args) {
		System.out.println("The possible arrangements are:");
		cb.put(0);
		String output = "There are totally "+ cb.showCount() +" kinds of arrangements.";
		System.out.println(output);
	}
}