题目链接：http://acm.fzu.edu.cn/problem.php?
pid=2170
贴个baka爷的代码留念。。
数据出的有问题。输入的字符串长度不超过1000
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<map>
#include<queue>
#include<stack>
#include<cmath>
#include<vector>
#define inf 0x3f3f3f3f
#define Inf 0x3FFFFFFFFFFFFFFFLL
#define eps 1e-9
#define pi acos(-1.0)
using namespace std;
typedef long long ll;
const int maxn=1000+2;
const int mod=1000000007;
int dp[maxn][maxn];
char str[maxn<<1];
int main()
{
//freopen("in.txt","r",stdin);
//freopen("out.txt","w",stdout);
int t,n;
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
memset(dp,0,sizeof(dp));
scanf("%s",str+1);
dp[0][0]=1;
int k;
for(int i=0;i<=n;++i)
for(int j=0;j<=n;++j)
{
if(!dp[i][j]) continue;
k=i+j+1;
if((i&1)&&(j&1))
{
if(str[k]=='B')
{
dp[i][j+1]+=dp[i][j];
dp[i+1][j]+=dp[i][j];
if(dp[i][j+1]>=mod) dp[i][j+1]-=mod;
if(dp[i+1][j]>=mod) dp[i+1][j]-=mod;
}
}
else if(i&1)
{
if(str[k]=='W')
{
dp[i][j+1]+=dp[i][j];
if(dp[i][j+1]>=mod) dp[i][j+1]-=mod;
}
else
{
dp[i+1][j]+=dp[i][j];
if(dp[i+1][j]>=mod) dp[i+1][j]-=mod;
}
}
else if(j&1)
{
if(str[k]=='W')
{
dp[i+1][j]+=dp[i][j];
if(dp[i+1][j]>=mod) dp[i+1][j]-=mod;
}
else
{
dp[i][j+1]+=dp[i][j];
if(dp[i][j+1]>=mod) dp[i][j+1]-=mod;
} }
else
{
if(str[k]=='W')
{
dp[i][j+1]+=dp[i][j];
dp[i+1][j]+=dp[i][j];
if(dp[i][j+1]>=mod) dp[i][j+1]-=mod;
if(dp[i+1][j]>=mod) dp[i+1][j]-=mod;
} }
}
int ans=dp[n][n];
printf("%d\n",ans);
}
return 0;
}