bzoj 4000 矩阵快速幂优化DP

建立矩阵,跑快速幂

 /**************************************************************
     Problem: 4000
     User: idy002
     Language: C++
     Result: Accepted
     Time:32 ms
     Memory:836 kb
 ****************************************************************/

 #include <cstdio>
 #include <cstring>
 #define M 6

 struct Matrix {
     unsigned v[<<M][<<M];
     const unsigned *operator[]( int i ) const { return v[i]; }
 };

 int n, m, p, k, bound;
 int attack[];
 int stat[<<M], id[<<M], stot;
 Matrix base, dest;

 void make_unit( Matrix &x ) {
     for( int i=; i<stot; i++ )
         for( int j=; j<stot; j++ )
             x.v[i][j] = i==j;
 }
 Matrix operator*( const Matrix &a, const Matrix &b ) {
     Matrix c;
     for( int i=; i<stot; i++ )
         for( int j=; j<stot; j++ ) {
             c.v[i][j] = ;
             for( int k=; k<stot; k++ )
                 c.v[i][j] += a[i][k]*b[k][j];
         }
     return c;
 }
 Matrix mpow( Matrix a, int b ) {
     Matrix rt;
     for( make_unit(rt); b; b>>=,a=a*a )
         if( b& ) rt=rt*a;
     return rt;
 }
 int getarea( int s, int a ) {
     int rt = ;
     for( int b=; b<m; b++ ) {
         if( (s>>b)& ) {
             int aa = a;
             if( b<k )
                 aa >>= k-b;
             else
                 aa <<= b-k;
             aa &= bound;
             rt |= aa;
         }
     }
     return rt;
 }
 void build() {
     stot = ;
     memset( id, -, sizeof(id) );
     for( int s=; s<=bound; s++ ) {
         if( getarea(s,attack[])&s ) continue;
         stat[stot]=s;
         id[s] = stot;
         stot++;
     }
     for( int s1=; s1<=bound; s1++ ) {
         if( id[s1]==- ) continue;
         for( int s2=; s2<=bound; s2++ ) {
             if( id[s2]==- ) continue;
             if( getarea(s1,attack[])&s2 ) continue;
             if( getarea(s2,attack[])&s1 ) continue;
             base.v[id[s1]][id[s2]] = ;
         }
     }
 }
 int main() {
     scanf( "%d%d%d%d", &n, &m, &p, &k );
     bound = (<<m)-;
     for( int i=; i<; i++ )
         for( int j=,o; j<p; j++ ) {
             scanf( "%d", &o );
             attack[i] = attack[i] | (o<<j);
         }
     attack[] ^= <<k;
     build();
     dest = mpow( base, n- );
     unsigned ans = ;
     for( int i=; i<stot; i++ )
         for( int j=; j<stot; j++ )
             ans += dest[i][j];
     printf( "%u\n", ans );
 }