CＦ 445A DZY Loves Chessboard

DZY loves chessboard, and he enjoys playing with it.

He has a chessboard of n rows and m columns. Some cells of the chessboard are bad, others are good. For every good cell, DZY wants to put a chessman on it. Each chessman is either white or black. After putting all chessmen, DZY wants that no two chessmen with the same color are on two adjacent cells. Two cells are adjacent if and only if they share a common edge.

You task is to find any suitable placement of chessmen on the given chessboard.

Input

The first line contains two space-separated integers n and m (1 ≤ n, m ≤ 100).

Each of the next n lines contains a string of m characters: the j-th character of the i-th string is either "." or "-". A "." means that the corresponding cell (in the i-th row and the j-th column) is good, while a "-" means it is bad.

Output

Output must contain n lines, each line must contain a string of m characters. The j-th character of the i-th string should be either "W", "B" or "-". Character "W" means the chessman on the cell is white, "B" means it is black, "-" means the cell is a bad cell.

If multiple answers exist, print any of them. It is guaranteed that at least one answer exists.

Examples
input
Copy
1 1
.

output
Copy
B

input
Copy
2 2
..
..

output
Copy
BW
WB

input
Copy
3 3
.-.
---
--.
output
Copy
B-B
---
--B

Note

In the first sample, DZY puts a single black chessman. Of course putting a white one is also OK.

In the second sample, all 4 cells are good. No two same chessmen share an edge in the sample output.

In the third sample, no good cells are adjacent. So you can just put 3 chessmen, no matter what their colors are.

【题意】

给一个ｎ＊ｍ的矩阵,用B和W填充‘.’，且相邻的位置不可以相同。

【分析1】

看做一个二分图，经典染色法
　

【代码1】

#include<cstdio>
#include<cstdlib>
using namespace std;
const int N=105;
int n,m,ans,dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
char mp[N][N];
void dfs(int x,int y,bool t){
	mp[x][y]=(t?'B':'W');
	for(int i=0;i<4;i++){
		int nx=x+dir[i][0];
		int ny=y+dir[i][1];
		if(nx<1||ny<1||nx>n||ny>m||mp[nx][ny]!='.') continue;
		dfs(nx,ny,t^1);
	}
}
inline void Init(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++) scanf("%s",mp[i]+1);
}
inline void Solve(){
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(mp[i][j]=='.') dfs(i,j,1);
		}
	}
	for(int i=1;i<=n;i++) puts(mp[i]+1);
}
int main(){
	Init();
	Solve();
	return 0;
}

【分析2】

规律：若当前位置为’.’,就i + j 时为奇数时输出W，反之输出B；若当前位置为’－’，直接输出
　

【代码2】

#include<cstdio>
#include<cstdlib>
using namespace std;
const int N=105;
int n,m;
char mp[N][N];
inline void Init(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++) scanf("%s",mp[i]+1);
}
inline void Solve(){
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(mp[i][j]=='-') printf("-");
			else printf("%s",(i+j)&1?"W":"B");
		}
		puts("");
	}
}
int main(){
	Init();
	Solve();
	return 0;
}

__EOF__

本文作者：shenben
本文链接：https://www.cnblogs.com/shenben/p/10353259.html
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