BZOJ4563 HAOI2016放棋子（高精度）

　　没看清题还以为是要求数最大匹配数量……注意到任意障碍不在同一行同一列，且恰好有n个障碍，不妨通过交换列使得第i行第i列均有障碍。那么就是个错排了。居然wa了一发简直没救。

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define ll long long
#define N 210
int read()
{
    int x=,f=;char c=getchar();
    while (c<''||c>'') {if (c=='-') f=-;c=getchar();}
    while (c>=''&&c<='') x=(x<<)+(x<<)+(c^),c=getchar();
    return x*f;
}
char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')) c=getchar();return c;}
int gcd(int n,int m){return m==?n:gcd(m,n%m);}
int n,f[N][N<<];
int main()
{
#ifndef ONLINE_JUDGE
    freopen("bzoj4563.in","r",stdin);
    freopen("bzoj4563.out","w",stdout);
    const char LL[]="%I64d\n";
#else
    const char LL[]="%lld\n";
#endif
    n=read();
    f[][]=;f[][]=f[][]=;
    for (int i=;i<=n;i++)
    {
        f[i][]=f[i-][];
        for (int j=;j<=f[i][];j++)
        {
            f[i][j]+=f[i-][j]+f[i-][j];
            if (f[i][j]>) f[i][j+]++,f[i][j]-=;
        }
        if (f[i][f[i][]+]) f[i][]++;
        for (int j=;j<=f[i][];j++)
        f[i][j]*=i-;
        for (int j=;j<=f[i][];j++)
        f[i][j+]+=f[i][j]/,f[i][j]%=;
        while (f[i][f[i][]+]) f[i][]++,f[i][f[i][]+]+=f[i][f[i][]]/,f[i][f[i][]]%=;
    }
    for (int i=f[n][];i>=;i--) cout<<f[n][i];
    return ;
}