codeforces840C On the Bench -- DP

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%%%Vectorxj

代码

#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>using namespace std;#define N 310#define M 1000000007int i,j,k,n,m,p,v[N],l,a[N],x,y,t,f[2][N],s;int c[N][N];int Ans;int* g;bool b;int main(){    scanf("%d",&n);    for(i=c[0][0]=1;i<=n;i++)c[i][0]=1;    for(i=1;i<=n;i++)    for(j=1;j<=i;j++)    c[i][j]=(c[i-1][j]+c[i-1][j-1])%M;    for(i=1;i<=n;i++){        scanf("%d",&x);        for(j=2;(t=j*j)<=x;j++)        while(!(x%t))x/=t;        a[i]=x;    }    sort(a+1,a+n+1);    for(i=1;i<=n;i=j+1){        for(j=i;a[j+1]==a[j];j++);        v[++l]=j-i+1;    }    sort(v+1,v+l+1);    f[0][(t=v[l])-1]=1;    for(p=l-1;p;p--,b^=1){        s=v[p];g=f[b^1];        for(i=0;i<=t+s;i++)g[i]=0;        for(i=0;i<t;i++){            x=f[b][i];            if(x){                for(j=1;j<=s;j++)                for(k=0;k<=i&&k<=j;k++)                if(t-i+1>=j-k){                    (g[i-k+s-j]+=1ll*x*c[i][k]%M*c[s-1][j-1]%M*c[t-i+1][j-k]%M)%=M;                }            }        }        t+=s;    }    Ans=f[b][0];    for(i=1;i<=l;i++)    for(j=2;j<=v[i];j++)    Ans=1ll*Ans*j%M;    cout<<Ans<<endl;    return 0;}

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