CF1051D Bicolorings 递推

考试T2,随便推一推就好了~

code:

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#include <bits/stdc++.h> 
#define N 1015
#define mod 998244353   
#define ll long long 
#define setIO(s) freopen(s".in","r",stdin) , freopen(s".out","w",stdout)
using namespace std;
ll f[N][N<<1][2][2];     
int main()
{
    // setIO("army");
    int i,j,n=2,m,k;
    scanf("%d%d",&m,&k);      
    f[1][1][0][0]=1ll; 
    f[1][1][1][1]=1ll; 
    f[1][2][1][0]=1ll;
    f[1][2][0][1]=1ll;  
    for(i=1;i<m;++i)
    {
        for(j=1;j<=k;++j)
        {     
            (f[i+1][j][0][0]+=(f[i][j][0][0]+f[i][j][0][1]+f[i][j][1][0])%mod)%=mod;    
            (f[i+1][j][1][1]+=(f[i][j][0][1]+f[i][j][1][0]+f[i][j][1][1])%mod)%=mod;  
            (f[i+1][j][0][1]+=f[i][j][0][1])%=mod;           
            (f[i+1][j][1][0]+=f[i][j][1][0])%=mod;  
            (f[i+1][j+1][0][0]+=f[i][j][1][1])%=mod; 
            (f[i+1][j+1][1][1]+=f[i][j][0][0])%=mod;     
            (f[i+1][j+1][0][1]+=(f[i][j][0][0]+f[i][j][1][1])%mod)%=mod;  
            (f[i+1][j+1][1][0]+=(f[i][j][0][0]+f[i][j][1][1])%mod)%=mod;    
            (f[i+1][j+2][0][1]+=f[i][j][1][0])%=mod; 
            (f[i+1][j+2][1][0]+=f[i][j][0][1])%=mod;   
        }
    }      
    printf("%lld\n",(f[m][k][0][0]+f[m][k][1][1]+f[m][k][0][1]+f[m][k][1][0])%mod);   
    return 0;
}

  

posted @   EM-LGH  阅读(90)  评论(0编辑  收藏  举报
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