八皇后问题

根据C程序改的Java的实现。以下为已知的N-皇后解数目。

public class Queens {
	private int[] queens = new int[8];	//解数组
	private int[] colflag =new int[8];	//列冲突标记
	private int[] flags1 = new int[15];	//对角线冲突标记
	private int[] flags2 = new int[15];	//对角线冲突标记
	private int roots ;
	private void trySet(int row){
		for (int column=0; column < 8; column++){
			if (colflag[column] == 0 
					&& flags1[row-column + 7]==0 
					&& flags2[row + column]==0 ){
				queens[row] = column;
				if (row <7){
					colflag[column] = 1;
					flags1[row-column + 7]= 1;
					flags2[row + column]=1;
					trySet(row+1);
				}else{
					roots ++;
					printit();
				}
				colflag[column] = 0;
				flags1[row-column + 7] = 0;
				flags2[row + column] = 0;
			}
		}
	}
	private void printit(){
		System.out.println (roots);
		for (int i = 0;i<8; i++){
			for (int j =0 ;j<8; j ++){
				if (queens[i]==j){
					System.out.print (" x");
				}else{
					System.out.print (" o");
				}
			}
			System.out.print("\n");
		}
		System.out.println("=================");
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		new Queens().trySet(0);		
	}
}

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