HDU 4812 D Tree （树上点分治）

#include <iostream>
#include <string.h>
#include <math.h>
#include <queue>
#include <algorithm>
#include <stdlib.h>
#include <map>
#include <set>
#include <stdio.h>
#include <time.h>
using namespace std;
#define LL __int64
#define pi acos(-1.0)
#pragma comment(linker, "/STACK:1024000000")
const int mod=1e6+3;
const int INF=0x3f3f3f3f;
const double eqs=1e-9;
const int MAXN=100000+10;
int head[MAXN], cnt, root, min1, ans1, ans2, tot, k, ff;
int siz[MAXN], vis[MAXN], best[MAXN*10], flag[MAXN*10];
LL Inv[MAXN*10], a[MAXN];
struct N
{
LL x;
int num;
}F[MAXN];
struct node
{
int v, next;
}edge[MAXN<<1];
void add(int u, int v)
{
edge[cnt].v=v;
edge[cnt].next=head[u];
head[u]=cnt++;
}
void getroot(int u, int fa, int s)
{
int max1=0;
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(v==fa||vis[v]) continue ;
getroot(v,u,s);
max1=max(max1,siz[v]);
}
max1=max(max1,s-siz[u]);
if(min1>max1){
min1=max1;
root=u;
}
}
void getsize(int u, int fa)
{
siz[u]=1;
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(v==fa||vis[v]) continue ;
getsize(v,u);
siz[u]+=siz[v];
}
}
LL ksm(LL x)
{
LL ans=1;
int k=mod-2;
while(k){
if(k&1) ans=ans*x%mod;
k>>=1;
x=x*x%mod;
}
return ans;
}
void getF(int u, int fa, LL val)
{
F[tot].x=val;
F[tot++].num=u;
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(v==fa||vis[v]) continue ;
getF(v,u,val*a[v]%mod);
}
}
void work(int u)
{
vis[u]=1;
int i, j;
LL tmp;
for(i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(vis[v]) continue ;
min1=INF;
getsize(v,u);
getroot(v,u,siz[v]);
work(root);
}
ff++;
best[1]=u;
flag[1]=ff;
for(i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(vis[v]) continue;
tot=0;
getF(v,u,a[v]);
for(j=0;j<tot;j++){
tmp=(LL)k*Inv[F[j].x*a[u]%mod]%mod;
if(flag[tmp]!=ff) continue ;
int minnum=min(best[tmp],F[j].num);
int maxnum=max(best[tmp],F[j].num);
if(ans1>minnum){
ans1=minnum;
ans2=maxnum;
}
else if(ans1==minnum&&ans2>maxnum) ans2=maxnum;
}
for(j=0;j<tot;j++){
if(flag[F[j].x]!=ff||best[F[j].x]>F[j].num){
best[F[j].x]=F[j].num;
flag[F[j].x]=ff;
}
}
}
vis[u]=0;
}
void init()
{
memset(head,-1,sizeof(head));
cnt=0;
memset(vis,0,sizeof(vis));
ans1=ans2=INF;
memset(flag,-1,sizeof(flag));
}
void init1()
{
Inv[0]=0;
for(int i=1;i<mod;i++){
Inv[i]=ksm((LL)i);
}
}
int main()
{
int n, i, u, v;
init1();
while(scanf("%d%d",&n,&k)!=EOF){
init();
ff=0;
for(i=1;i<=n;i++){
scanf("%I64d",&a[i]);
}
for(i=1;i<n;i++){
scanf("%d%d",&u,&v);
add(u,v);
add(v,u);
}
min1=INF;
getsize(1,-1);
getroot(1,-1,n);
work(root);
if(ans1==INF) puts("No solution");
else printf("%d %d\n",ans1,ans2);
}
return 0;
}