import java.io.*;
import java.util.Scanner;


public class Main{
	private static int n;
	private static char[][] board; //记录棋盘状态
	private static boolean[] place_C; //记录这列是否可以放旗子
	private static int count = 0;     //方案数
	private static int numPlaced = 0; //已放旗子数目
	private static int k;   //要放的旗子数目
	
	public static void main(String[] args) throws IOException {
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader br = new BufferedReader(isr);
		Scanner s = new Scanner(System.in);
		while(true) {
			n = s.nextInt();
			k = s.nextInt();
			if(n == -1 && k == -1)
				return;
			board = new char[n][n];
			place_C = new boolean[n];
			int r = 0;
			String test = br.readLine();
			while(test!=null) {
				for(int i=0; i<n; i++)
					board[r][i] = test.charAt(i);
				r++;
				if(r == n)
					break;
				test = br.readLine();
			}
			dfs(0);
			System.out.println(count);
			count = 0;
		}
	}
	
	public static boolean canPlace(int i, int j) {
		return !place_C[j] && board[i][j] == '#';
	}
	
	
	public static void dfs(int i) {
		if(numPlaced == k) {
			count++;
			return;
		}
		if(i >= n)
			return;
		int j;
		for(j=0; j<n; j++) {
			if(canPlace(i,j)) {
				place_C[j] = true;
				numPlaced++;
				dfs(i+1);
				place_C[j] = false;
				numPlaced--;
			}
		}
		dfs(i+1);
	}
}

• Re:java 怎么总提交出错呢？谁帮帮我看看是不是代码 错了谢谢啊 (1492) gedoua 2009-08-01 15:04:24