2017-10-18 NOIP模拟赛

#include<iostream>
#include<cstdio>
#include<ctime>
#include<cstdlib>
#define maxn 301
using namespace std;
int n,a[maxn],q[maxn],cnt[maxn];
long long sz[maxn];
bool vis[maxn];
int gcd(int x,int y){
    if(y==0)return x;
    else return gcd(y,x%y);
}
void dfs(int pos,int now){
    if(clock()>=980){
        puts("0.000000000 1.000000000");
        exit(0);
    }
    if(now==1){
        if((pos&1)==0)cnt[pos]++;
        return;
    }
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            vis[i]=1;
            dfs(pos+1,gcd(now,a[i]));
            vis[i]=0;
        }
    }
}
int main(){
    //freopen("Cola.txt","r",stdin);
    freopen("cards.in","r",stdin);freopen("cards.out","w",stdout);
    scanf("%d",&n);
    sz[1]=n;
    for(int i=2;i<=n;i++)sz[i]=sz[i-1]*(n-i+1);
    for(int i=1;i<=n;i++)scanf("%d",&a[i]);
    dfs(0,0);
    double ans=0;
    for(int i=2;i<=n;i+=2)
        ans+=(double)cnt[i]/(double)sz[i];
    printf("%.9lf ",ans);
    puts("1.000000000");
}

#include<iostream>
#include<cstdio>
#include<cstring>
#define maxn 100010
#define mod 1000000007
using namespace std;
int n,q[maxn],fa[maxn],sz[maxn],w[maxn],cut[maxn],ans,map[maxn];
int num,head[maxn],mx[maxn],vis[maxn];
struct node{
    int from,to;
}E[maxn];
struct Node{
    int to,pre;
}e[maxn];
int find(int x){
    if(x==fa[x])return x;
    else return fa[x]=find(fa[x]);
}
void dfs(int x,int father,int stx,int sty,int wnow){
    for(int i=head[x];i;i=e[i].pre){
        int to=e[i].to;
        if(to==father)continue;
        if(mx[to]<mx[sty]+wnow+w[to]){
            mx[to]=mx[sty]+wnow+w[to];
            map[to]=map[sty];
            dfs(to,x,stx,sty,wnow+w[to]);
        }
    }
}
void connect(int x,int y){
    int f1=find(x),f2=find(y);
    int now=mx[x]+mx[y];
    fa[f2]=f1;
    if(now>sz[f1]&&now>sz[f2]){
        sz[f1]=now;
        sz[f2]=0;
    }
    else{
        sz[f1]=max(sz[f1],sz[f2]);
        sz[f2]=0;
    }
    dfs(x,x,x,y,w[x]);
    dfs(y,y,y,x,w[y]);
    int xx=map[x],yy=map[y];
    int maxx=mx[x],maxy=mx[y];
    map[map[x]]=yy;map[map[y]]=xx;
    if(mx[x]<maxy+w[x]){mx[x]=maxy+w[x];map[x]=yy;}
    if(mx[y]<maxx+w[y]){mx[y]=maxx+w[y];map[y]=xx;}
}
void Insert(int from,int to){
    e[++num].to=to;
    e[num].pre=head[from];
    head[from]=num;
    e[++num].to=from;
    e[num].pre=head[to];
    head[to]=num;
}
int qread(){
    int i=0;
    char ch=getchar();
    while(ch<‘0‘||ch>‘9‘)ch=getchar();
    while(ch<=‘9‘&&ch>=‘0‘){i=i*10+ch-‘0‘;ch=getchar();}
    return i;
}
int main(){
    freopen("forest.in","r",stdin);freopen("forest.out","w",stdout);
    //freopen("Cola.txt","r",stdin);
    n=qread();
    q[n]=1;
    for(int i=1;i<=n;i++){
        w[i]=qread();
        fa[i]=i,sz[i]=w[i];
        mx[i]=w[i];
        map[i]=i;
        q[n]=(1LL*w[i]*q[n])%mod;
    }
    for(int i=1;i<n;i++)scanf("%d%d",&E[i].from,&E[i].to);
    for(int i=1;i<n;i++)scanf("%d",&cut[i]);
    for(int i=n-1;i>=1;i--){
        connect(E[cut[i]].from,E[cut[i]].to);
        Insert(E[cut[i]].from,E[cut[i]].to);
        long long ans=1;
        memset(vis,0,sizeof(vis));
        for(int j=1;j<=n;j++){
            int now=find(j);
            if(!vis[now]){
                vis[now]=1;
                ans=ans*sz[now];
                if(ans>=mod)ans%=mod;
            }
        }
        q[i]=(int)ans;
        //for(int j=1;j<=n;j++)printf("%d %d %d\n",j,map[j],mx[j]);puts("");
    }
    for(int i=1;i<=n;i++){
        printf("%d\n",q[i]);
    }
    return 0;
}
/*
8
2 3 6 3 9 4 5 6
4 8
3 5
4 1
1 3
1 2
6 5
7 5
2
6
3
1
7
4
5
*/