2016弱校联萌十一专场10.2

#include<cstdio>
#include<algorithm>
#include<cstring>
#define F(i,a,b) for(int i=a;i<=b;i++)
#define mst(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef pair<int,int>P;

const int N=1e5+200,DEG=18;
int g[N],v[N*2],nxt[N*2],ed,n,m,q,eed,cnt,id[N],Q[N];
int dep[N],fa[N][DEG],dfn[N],idx,d[201][N];
P vec[N];
bool vis[N];

inline void adg(int x,int y){v[++ed]=y,nxt[ed]=g[x],g[x]=ed;}
inline void up(int &a,int b){if(a>b)a=b;}

void dfs(int u=1,int pre=0)
{
    dep[u]=dep[pre]+1,fa[u][0]=pre,dfn[u]=++idx;
    F(i,1,DEG-1)fa[u][i]=fa[fa[u][i-1]][i-1];
    for(int i=g[u];i;i=nxt[i])if(!dfn[v[i]])dfs(v[i],u);
    else if(v[i]!=pre&&dfn[v[i]]<dfn[u])vec[++eed]=P(u,v[i]);
}

int LCA(int a,int b){
    if(dep[a]>dep[b])a^=b,b^=a,a^=b;
    if(dep[a]<dep[b])F(i,0,DEG-1)if((dep[b]-dep[a])&(1<<i))b=fa[b][i];
    if(a!=b)for(int i=DEG-1;i<0?a=fa[a][0]:0,i>=0;i--)
    if(fa[a][i]!=fa[b][i])a=fa[a][i],b=fa[b][i];
    return a;
}

void bfs(int *d,int S)
{
    mst(vis,0);
    int head=1,tail=0,now;
    Q[++tail]=S,vis[S]=1,d[S]=0;
    while(head<=tail)for(int i=g[now=Q[head++]];i;i=nxt[i])
    if(!vis[v[i]])vis[v[i]]=1,d[v[i]]=d[now]+1,Q[++tail]=v[i];
}

int main()
{
    while(~scanf("%d%d%d",&n,&m,&q))
    {
        int x,y;ed=idx=eed=cnt=0;
        mst(g,0),mst(dfn,0),mst(fa,0),mst(id,0);
        F(i,1,m)scanf("%d%d",&x,&y),adg(x,y),adg(y,x);
        dfs();
        F(i,1,eed)
        {
            if(!id[vec[i].first])id[vec[i].first]=++cnt,bfs(d[cnt],vec[i].first);
            if(!id[vec[i].second])id[vec[i].second]=++cnt,bfs(d[cnt],vec[i].second);
        }
        F(i,1,q)
        {
            scanf("%d%d",&x,&y);
            int ans=dep[x]+dep[y]-2*dep[LCA(x,y)];
            F(j,1,eed)
            {
                int u=id[vec[j].first],v=id[vec[j].second];
                up(ans,d[u][x]+d[v][y]+1),up(ans,d[v][x]+d[u][y]+1);
            }
            printf("%d\n",ans);
        }
    }
    return 0;
}

#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <string.h>
typedef long long LL;
const LL maxn=1e5+10;
const LL mod=1e9+7;
using namespace std;
struct Tree
{
    LL to,next,c;
} edge[maxn*2];
LL Inv[30*maxn];
LL tot,head[maxn];
LL jc[maxn*30];
LL sum;
void Init()
{
    Inv[0]=1;
    Inv[1] = 1;
    for(LL i=2; i<25*maxn; i++)
        Inv[i] = (mod-mod/i)*Inv[mod%i]%mod;
    for(LL i=2; i<25*maxn; i++)
        Inv[i] = (Inv[i-1]*Inv[i])%mod;
}
void init()
{
    tot=0;
    memset(head,-1,sizeof(head));
}
void add_edge(LL u,LL v,LL c)
{
    edge[tot].to=v;
    edge[tot].c=c;
    edge[tot].next=head[u];
    head[u]=tot++;
}

void init2()
{
    jc[0]=1;
    for(LL i=1; i<maxn*30; i++)
        jc[i]=((jc[i-1]*i)%mod);
}
LL road[maxn];
void  dfs(LL u,LL pre)
{
    road[u]=0;
    for(LL i=head[u]; i!=-1; i=edge[i].next)
    {
        LL v=edge[i].to;
        if(v==pre) continue;
        dfs(v,u);
        road[u]+=edge[i].c;
        sum=(((sum*jc[edge[i].c*2])%mod)*Inv[edge[i].c])%mod;
        sum=((sum*  jc[(road[v]+edge[i].c-1)]%mod)*Inv[edge[i].c-1] )%mod;
        sum=(sum*Inv[road[v]])%mod;
    }
    sum=(sum*jc[road[u]])%mod;
}

int main()
{
    Init();
    init2();
    LL n,u,v,c;
    while(scanf("%lld",&n)!=-1)
    {
        sum=1;
        init();
        for(LL i=1; i<n; i++)
        {
            scanf("%lld%lld%lld",&u,&v,&c);
            add_edge(u,v,c);
            add_edge(v,u,c);
        }
        dfs(1,0);
        printf("%lld\n",sum);
    }
    return 0;
}