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  • [BZOJ4000][TJOI2015]棋盘(状压DP+矩阵快速幂)

    题意极其有毒,注意给的行列都是从0开始的。

    状压DP,f[i][S]表示第i行状态为S的方案数,枚举上一行的状态转移。$O(n2^{2m})$

    使用矩阵加速,先构造矩阵a[S1][S2]表示上一行为S1是下一行是否能为S2,快速幂加速后得解。$O(2^{3m}m^2+2^{3m}log n)$

     1 #include<cstdio>
     2 #include<cstring>
     3 #include<algorithm>
     4 #define rep(i,l,r) for (int i=(l); i<=(r); i++)
     5 typedef unsigned int ul;
     6 using namespace std;
     7 
     8 const int N=70;
     9 ul ans;
    10 int n,m,p,k,ed,x,tot;
    11 struct P{ int x,y; }d[110];
    12 
    13 struct Mat{
    14     ul a[N][N];
    15     ul* operator [](int x){ return a[x]; }
    16     Mat (){ memset(a,0,sizeof(a)); }
    17 }a,res;
    18 
    19 Mat mul(Mat a,Mat b){
    20     Mat c;
    21     rep(i,0,ed) rep(j,0,ed) rep(k,0,ed) c[i][k]+=a[i][j]*b[j][k];
    22     return c;
    23 }
    24 
    25 Mat ksm(Mat a,int b){
    26     Mat res;
    27     rep(i,0,ed) res[i][i]=1;
    28     for (; b; a=mul(a,a),b>>=1)
    29         if (b & 1) res=mul(res,a);
    30     return res;
    31 }
    32 
    33 int main(){
    34     freopen("bzoj4000.in","r",stdin);
    35     freopen("bzoj4000.out","w",stdout);
    36     scanf("%d%d%d%d",&n,&m,&p,&k); k++; ed=(1<<m)-1;
    37     rep(i,1,3) rep(j,1,p){
    38         scanf("%d",&x);
    39         if (x) d[++tot]=(P){i-2,j-k};
    40     }
    41     rep(S1,0,ed) rep(S2,0,ed){
    42         bool flag=0;
    43         rep(i,0,m-1) if (S1&(1<<i))
    44             rep(j,0,m-1) if (S2&(1<<j))
    45                 rep(k,1,tot) if ((d[k].x==1 && d[k].y==j-i) || (d[k].x==-1 && d[k].y==i-j))
    46                     { flag=1; break; }
    47         rep(i,0,m-2) if (S2&(1<<i))
    48             rep(j,i+1,m-1) if (S2&(1<<j))
    49                 rep(k,1,tot) if (d[k].x==0 && (d[k].y==j-i || d[k].y==i-j))
    50                     { flag=1; break; }
    51         a[S1][S2]=!flag;
    52     }
    53     res[0][0]=1; res=mul(res,ksm(a,n));
    54     rep(i,0,ed) ans+=res[0][i];
    55     printf("%u
    ",ans);
    56     return 0;
    57 }
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  • 原文地址:https://www.cnblogs.com/HocRiser/p/9870643.html
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