C++11(clang++ 3.9) 解法, 执行用时: 108ms, 内存消耗: 31468K, 提交时间: 2020-05-13 18:45:54

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;
#define N 205

int n,k,now;
int boy[N],girl[N];
struct data{int a[N],len,f;}zero,one,ans,c[N][N],f[2][N],mul[N];

data jian(data a,data b)
{
    data ans=zero;int len=max(a.len,b.len);
    if (a.len<b.len) ans.f=-1,swap(a,b);
    else if (a.len==b.len)
    {
        for (int i=len;i>=1;--i)
            if (a.a[i]>b.a[i]) break;
            else if (a.a[i]<b.a[i])
            {
                ans.f=-1;
                swap(a,b);
                break;
            }
    }
    for (int i=1;i<=len;++i)
    {
        if (a.a[i]<b.a[i])
        {
            --a.a[i+1];
            a.a[i]+=10000;
        }
        ans.a[i]=a.a[i]-b.a[i];
    }
    while (len>1&&!ans.a[len]) --len;
    ans.len=len;
    if (ans.len==1&&ans.a[1]==0) ans.f=1;
    return ans;
}
data jia(data a,data b)
{
    data ans=zero;
    if (a.f!=b.f)
    {
        if (a.f==1)
        {
            b.f=1;
            return jian(a,b);
        }
        else
        {
            a.f=1;
            return jian(b,a);
        }
    }
    ans.f=a.f;
    int len=max(a.len,b.len);
    for (int i=1;i<=len;++i) ans.a[i]=a.a[i]+b.a[i];
    for (int i=1;i<=len;++i)
    {
        ans.a[i+1]+=ans.a[i]/10000;
        ans.a[i]%=10000;
    }
    if (ans.a[len+1]) ++len;
    ans.len=len;
    if (ans.len==1&&ans.a[1]==0) ans.f=1;
    return ans;
}
data cheng(data a,data b)
{
    int len=a.len+b.len-1;
    data ans=zero;ans.f=(a.f==b.f)?1:-1;
    for (int i=1;i<=a.len;++i)
        for (int j=1;j<=b.len;++j)
            ans.a[i+j-1]+=a.a[i]*b.a[j];
    for (int i=1;i<=len;++i)
    {
        ans.a[i+1]+=ans.a[i]/10000;
        ans.a[i]%=10000;
    }
    while (ans.a[len+1])
    {
        ++len;
        ans.a[len+1]+=ans.a[len]/10000;
        ans.a[len]%=10000;
    }
    ans.len=len;
    if (ans.len==1&&ans.a[1]==0) ans.f=1;
    return ans;
}
void print(data a)
{
    if (a.f==-1) putchar('-');
    for (int i=a.len;i>=1;--i)
    {
        if (i==a.len||a.a[i]>=1000) printf("%d",a.a[i]);
        else if (a.a[i]>=100) printf("0%d",a.a[i]);
        else if (a.a[i]>=10) printf("00%d",a.a[i]);
        else printf("000%d",a.a[i]);
    }
    puts("");
}
void init()
{
    zero.len=1,zero.f=1;one.len=one.a[1]=one.f=1;
    mul[0]=one;
    for (int i=1;i<=n;++i)
    {
        data x=zero;x.a[1]=i;
        mul[i]=cheng(mul[i-1],x);
    }
    for (int i=0;i<=n;++i) c[i][0]=one;
    for (int i=1;i<=n;++i)
        for (int j=1;j<=n;++j)
            c[i][j]=jia(c[i-1][j],c[i-1][j-1]);
}
int main()
{
    scanf("%d%d",&n,&k);
    init();
    for (int i=1;i<=n;++i) scanf("%d",&boy[i]);
    for (int i=1;i<=n;++i) scanf("%d",&girl[i]);
    sort(boy+1,boy+n+1);sort(girl+1,girl+n+1);
    for (int i=0;i<=1;++i)
        for (int j=0;j<=n;++j)
            f[i][j]=zero;
    for (int i=0;i<=1;++i) f[i][0]=one;
    now=0;
    for (int i=1;i<=n;++i)
    {
        while (now<n&&boy[now+1]<girl[i])
            ++now;
        for (int j=1;j<=i;++j)
        {
            f[i&1][j]=f[(i-1)&1][j];
            data x=zero;x.a[1]=now-j+1;
            x=cheng(f[(i-1)&1][j-1],x);
            if (now>j-1) f[i&1][j]=jia(f[i&1][j],x);
        }
    }
    ans=zero;
    for (int i=0;i<=k;++i)
        for (int j=i,opt=1;j<=n;++j,opt=-opt)
        {
            data x=f[n&1][j];
            x=cheng(x,mul[n-j]);x=cheng(x,c[j][i]);
            if (opt==-1) x.f=-x.f;
            ans=jia(ans,x);
        }
    print(ans);
}