poj1321--Checkerboard problem

Description

In a given shape of the chessboard (the shape may be irregular) on the top of the pieces, chess pieces no difference. If you need to place any of the two pieces in the same row or column in the chessboard, please program the chessboard with a given shape and size, and put all the feasible arrangement C for the K pieces.

Input

The input contains multiple sets of test data.

The first row of each set of data is two positive integers, n K, separated by a space, indicating that the chessboard will be described in a n*n matrix and the number of pieces to be placed. N <= 8, K <= N

When 1-1 indicates the end of the input.

The next n lines describe the shape of the chessboard: N characters per line, where # represents the board area. Represents an empty area (the data guarantees that no extra blank lines or blank columns appear).

Output

For each set of data, give a line of output, the output is placed in the number of programs C (Data Assurance c<2^31).

Sample Input

2 1

#.

.#

4 4

...#

.. #.

.#..

#...

-1-1

Sample Output

2

1

Test instructions: Chess pieces can not be placed in the same row, or the DFS is not ripe, think of a half-day, just start thinking is the record path, remove peers with the same column, write a half-day, no A out, and later on the Internet to check the code of others, a simple DFS to take care of. Tears rushed ah, immediately to participate in the competition, simple DFS will not ....

#include <iostream> #include <string.h> #include <stdio.h> #include <algorithm>using namespace Std;int count1;                      Defined on the outside Char mp[10][10];int vis[10];int n,k;void dfs (int x,int t) {    if (t==k)    {      count1++;      return;    }    else if (x>=n)        return;   else    {for     (int i=x;i<n;i++)                   //Core code control does not peer for        (int j=0;j<n;j++)        {            if (mp[i][j]== ' # ' &&!vis[j])     //tag array control different columns            {                vis[j]=1;                DFS (i+1,t+1);              Number of lines per line plus 1                vis[j]=0;}}}    int main () {    while (cin>>n>>k)    {        if (n==-1&&k==-1) is break            ;        for (int i=0;i<n;i++)           cin>>mp[i];        count1=0;        memset (vis,0,sizeof (Vis));        DFS (0,0);        cout<<count1<<endl;    }    return 0;}

poj1321--Checkerboard problem