luogu CF600E Lomsat gelral |dsu on tree

一棵树有n个结点，每个结点都是一种颜色，每个颜色有一个编号，求树中每个子树的最多的颜色编号的和。

---

启发式搜索

#include<vector>
#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;
#define ll long long
const int MAXN=1e5+10;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
int N,col[MAXN],son[MAXN],siz[MAXN],cnt[MAXN],Mx,Son;
ll sum=0,ans[MAXN];
vector<int>v[MAXN];
inline void dfs(int x,int fa){//预处理重边
	siz[x]=1;
	for(int i=0;i<v[x].size();i++){
		int to=v[x][i];
		if(to==fa)continue;
		dfs(to,x);
		siz[x]+=siz[to];
		if(siz[to]>siz[son[x]])son[x]=to;
	}
}
inline void add(int x,int fa,int val){
	cnt[col[x]]+=val;
	if(cnt[col[x]]>Mx)Mx=cnt[col[x]],sum=col[x];
	else if(cnt[col[x]]==Mx)sum+=(ll)col[x];
	for(int i=0;i<v[x].size();i++){
		int to=v[x][i];
		if(to==fa||to==Son)continue;
		add(to,x,val);
	}
}
inline void dfs2(int x,int fa,int opt){
	for(int i=0;i<v[x].size();i++){
		int to=v[x][i];
		if(to==fa||to==son[x])continue;
		dfs2(to,x,0);//轻边
	}
	if(son[x])dfs2(son[x],x,1),Son=son[x];
	add(x,fa,1); Son=0;
	ans[x]=sum;
	if(!opt)add(x,fa,-1),sum=0,Mx=0;
}
signed main(){
	N=read();
	for(int i=1;i<=N;i++)col[i]=read();
	for(int i=1;i<N;i++){
		int x=read(),y=read();
		v[x].push_back(y);
		v[y].push_back(x);
	}
	dfs(1,0);
	dfs2(1,0,0);
	for(int i=1;i<=N;i++)
	printf("%lld ",ans[i]);
	return 0;
}