bzoj:4762: 最小集合

原题链接：http://www.lydsy.com/JudgeOnline/problem.php?id=4762

mark一下，有空要好好弄懂

#include<cstdio>

#include<algorithm>

using namespace std;

int read_p,read_ca;

inline int read(){

    read_p=;read_ca=getchar();

    while(read_ca<''||read_ca>'') read_ca=getchar();

    while(read_ca>=''&&read_ca<='') read_p=read_p*+read_ca-,read_ca=getchar();

    return read_p;

}

const int MOD=1e9+;

int n,a,mmh[][][];

inline void M(int &x){while(x>=MOD)x-=MOD;while(x<)x+=MOD;}

int main(){

    register int i,j,k;

    n=read();mmh[][][]=;

    for (i=;i<=n;i++){

        a=-read();

        for (j=;j<;j++)

        for (k=j;;k=(k-)&j){

            mmh[i&][j][k]=mmh[i&^][j][k];

            if (!k) break;

        }

        for (j=;j<;j++)

        for (k=j;;k=(k-)&j){

            M(mmh[i&][j|a][k^(k&a)]+=mmh[i&^][j][k]);

            M(mmh[i&][j|a][(k^(k&a))|(a^(j&a))]-=mmh[i&^][j][k]);

            if (!k) break;

        }

    }

    printf("%d\n",mmh[n&][][]);

}