bzoj2958: 序列染色&&3269: 序列染色

DP这种东西，考场上就只能看命了。。

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;
typedef long long LL;
const int mod=1e9+;

LL f[][][];//f[i][j][k]表示第i个位置 j=0没有连续K个的B或W,j=1只有B有,j=2 BW都有  k表示放B还是W
int b[],w[];
char ss[];
int main()
{
    int n,K;
    scanf("%d%d",&n,&K);
    scanf("%s",ss+);
    for(int i=;i<=n;i++)
    {
        b[i]=b[i-];w[i]=w[i-];
             if(ss[i]=='B')b[i]++;
        else if(ss[i]=='W')w[i]++;
    }
    memset(f,,sizeof(f));f[][][]=;
    for(int i=;i<=n;i++)
    {
        if(ss[i]=='B'||ss[i]=='X')
        {
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
        }
        if(ss[i]=='W'||ss[i]=='X')
        {
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
            f[i][][]=(f[i][][]+(f[i-][][]+f[i-][][])%mod)%mod;
        }
        if(i<K)continue;
        if((ss[i]=='B'||ss[i]=='X')&&w[i]==w[i-K])
        {
            f[i][][]=(f[i][][]+f[i-K][][])%mod;
            f[i][][]=(f[i][][]-f[i-K][][]+mod)%mod;
        }
        if((ss[i]=='W'||ss[i]=='X')&&b[i]==b[i-K])
        {
            f[i][][]=(f[i][][]+f[i-K][][])%mod;
            f[i][][]=(f[i][][]-f[i-K][][]+mod)%mod;
        }
    }
    printf("%lld\n",(f[n][][]+f[n][][])%mod);
    return ;
 }