[黑科技]树上启发式合并 初步

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<string>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#define rep(i,j,k) for(register int i=j;i<=k;i++)
#define rrep(i,j,k) for(register int i=j;i>=k;i--)
#define erep(i,u) for(register int i=head[u];~i;i=nxt[i])
#define iin(a) scanf("%d",&a)
#define lin(a) scanf("%lld",&a)
#define din(a) scanf("%lf",&a)
#define s0(a) scanf("%s",a)
#define s1(a) scanf("%s",a+1)
#define print(a) printf("%lld",(ll)a)
#define enter putchar(‘\n‘)
#define blank putchar(‘ ‘)
#define println(a) printf("%lld\n",(ll)a)
#define IOS ios::sync_with_stdio(0)
#define clr(a,b) memset(a,b,sizeof a)
using namespace std;
const int maxn = 1e5+11;
const int oo = 0x3f3f3f3f;
const double eps = 1e-7;
typedef long long ll;
ll read(){
    ll x=0,f=1;register char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
int to[maxn<<1],nxt[maxn<<1],head[maxn],tot;
int sz[maxn],st[maxn],ed[maxn],pre[maxn],tot2;
int cnt[maxn],col[maxn],C;
void init(){
    memset(head,-1,sizeof head);
    memset(cnt,0,sizeof cnt);
    tot=tot2=0;
}
void add(int u,int v){
    to[tot]=v;nxt[tot]=head[u];head[u]=tot++;
    swap(u,v);
    to[tot]=v;nxt[tot]=head[u];head[u]=tot++;
}
void prepare(int u,int p){
    sz[u]=1;
    st[u]=++tot2;pre[tot2]=u;
    erep(i,u){
        int v=to[i];
        if(v!=p){
            prepare(v,u);
            sz[u]+=sz[v];
        }
    }
    ed[u]=tot2;
}
void dfs(int u,int p,bool keep){
    int mx=1,son=-1;
    erep(i,u){
        int v=to[i];
        if(v!=p&&sz[v]>mx){
            mx=sz[v];
            son=v;
        }
    }
    erep(i,u){
        int v=to[i];
        if(v==p||v==son)continue;
        dfs(v,u,0);
    }
    if(~son) dfs(son,u,1);
    erep(i,u){
        int v=to[i];
        if(v==p||v==son)continue;
        rep(i,st[v],ed[v]) cnt[col[pre[i]]]++;
    }
    cnt[col[u]]++;
    cout<<"Subtree "<<u<<endl;
    rep(i,1,C){
        if(cnt[i]>0) cout<<"Color "<<i<<" has "<<cnt[i]<<" vertices"<<endl; 
    } 
    cout<<endl;
    if(!keep) rep(i,st[u],ed[u]) cnt[col[pre[i]]]--;
}
int main(){
    int n,m;
    while(cin>>n>>C){
        init();m=n-1;
        rep(i,1,n) col[i]=read();
        rep(i,1,m){
            int u=read();
            int v=read();
            add(u,v);
        }
        prepare(1,0);
        rep(i,1,n) cout<<i<<" "<<sz[i]<<" "<<st[i]<<" "<<ed[i]<<endl;
        cout<<endl;
        rep(i,1,tot2) cout<<i<<" "<<pre[i]<<endl;
        dfs(1,0,0);
    }
    return 0;
}

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