7.26T1四分图匹配

#include <cstdio>

bool ab[40][40],ac[40][40],bd[40][40],cd[40][40];
int e[1200000];
int i,j,n;
long long s;

inline void dfs(int x,int bb,int cc,int dd)
{
    if (x==n+1)
        s++;
    else
    {
        for (int b=bb;b!=0;b=b-(b&(-b)))
        {
            int i=e[b&(-b)];
            if (ab[x][i])
                for (int c=cc;c!=0;c=c-(c&(-c)))
                {
                    int j=e[c&(-c)];
                    if (ac[x][j])
                        for (int d=dd;d!=0;d=d-(d&(-d)))
                        {
                            int k=e[d&(-d)];
                            if ((bd[i][k]) && (cd[j][k]))
                                dfs(x+1,bb^(1<<(i-1)),cc^(1<<(j-1)),dd^(1<<(k-1)));
                        }
                }
        }
    }
    return;
}

int main()
{
    scanf("%d",&n);
    for (i=1;i<=n;i++)
        for (j=1;j<=n;j++)
            ab[i][j]=ac[i][n+i-j]=bd[j][i+j-1]=cd[n+i-j][i+j-1]=true;
    for (i=1,j=1;j<=2*n;i=i<<1,j++)
        e[i]=j;
    dfs(1,(1<<n)-1,(1<<(2*n-1))-1,(1<<(2*n-1))-1);
    printf("%d\n%lld\n",n,s);
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
typedef int ll;
inline ll read()
{
    ll s=0; bool f=0; char ch=‘ ‘;
    while(!isdigit(ch)) {f|=(ch==‘-‘); ch=getchar();}
    while(isdigit(ch)) {s=(s<<3)+(s<<1)+(ch^48); ch=getchar();}
    return (f)?(-s):(s);
}
#define R(x) x=read()
inline void write(ll x)
{
    if(x<0) {putchar(‘-‘); x=-x;}
    if(x<10) {putchar(x+‘0‘); return;}
    write(x/10); putchar((x%10)+‘0‘);
}
#define W(x) write(x),putchar(‘ ‘)
#define Wl(x) write(x),putchar(‘\n‘)
int n;
int main()
{
    freopen("quadripartite.in","r",stdin);
    freopen("quadripartite.out","w",stdout);
    R(n);
    Wl(n);
    if(n==3) puts("78");
    else if(n==4) puts("4196");
    else if(n==5) puts("456920");
    else if(n==6) puts("88142144");
    else puts("27913176688");
    return 0;
}