348B - Apple Tree 树形DP（好题

赛中没调出来。。但很早就想出lcm的正解还是挺开心的。。

1/22的提交，调了2小时，先是遇到各种爆long long的问题，最后的问题是邻接表处理子结点没完全处理好

#include<bits/stdc++.h>
#include<stdio.h>
#include<algorithm>
#include<queue>
#include<string.h>
#include<iostream>
#include<math.h>
#include<set>
#include<map>
#include<vector>
#include<iomanip>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define FOR(a) for(int i=1;i<=a;i++)
const int inf=0x3f3f3f3f;
const long long Linf=9e18;
const int maxn=1e5+9; 

int n;
vector<int>G[maxn];

ll weight[maxn];

ll ans=0;
int flag;

ll g[maxn];	//g[u]表示u节点的份尺寸

ll gcd(ll a,ll b){
	return b==0?a:gcd(b,a%b);
}
ll lcm(ll a,ll b){
	return a/gcd(a,b)*b;
}

void dfs(int u,int fa){	
	if(flag==9)return;
	int sz=G[u].size();

	if(u!=1 && sz==1){
		return;
	}
	
	ll minn=Linf;
	for(int i=0;i<sz;i++){
		int v=G[u][i];if(v==fa)continue;
		dfs(v,u);
		if(flag==9)return;
		minn=min(minn,weight[v]);
		g[u]=lcm(g[u],g[v]);
		if(g[u]>minn){
			flag=9;return;
		}
	}
	
	ll nx;if(u==1)nx=G[u].size();
	else nx=G[u].size()-1;

	//ll minus=minn%g[u];
	ll minus=minn-(minn/g[u])*g[u];

	if(minus==minn){
		flag=9;return;
	}
	g[u]*=nx;
	minn-=minus;

	/*
	for(int i=0;i<sz;i++){
		int v=G[u][i];if(v==fa)continue;
		ans+=weight[v]-minn;
		weight[v]=minn;
	}
	*/
	weight[u]=minn*(nx);
}

int main(){
	scanf("%d",&n);
	FOR(n)g[i]=1;
	ll cnt=0;
	FOR(n){scanf("%lld",&weight[i]);cnt+=weight[i];}
	FOR(n-1){
		int u,v;
		scanf("%d%d",&u,&v);
		G[u].pb(v);
		G[v].pb(u);
	}
	flag=0;
	dfs(1,1);

	if(flag==9){
		printf("%lld\n",cnt);return 0;
	}
	printf("%lld\n",cnt-weight[1]);
}