求问有些什么注意事项

代码如下

// Problem: CF1746D Paths on the Tree
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/CF1746D
// Memory Limit: 250 MB
// Time Limit: 3000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

// Author:zymooll

#include<bits/stdc++.h>
//#define getchar getchar_unlocked
//#define putchar putchar_unlocked
#define int long long
using namespace std;
int read(){
	int s=0,w=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')w=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		s=s*10+c-'0';
		c=getchar();
	}
	return s*w;
}
void print(int x){
	if(x<0){
		putchar('-');
		x=-x;
	}
	if(x>=10)print(x/10);
	putchar(x%10+'0');
	return;
}
int t;
int n,k;
int s[200010];
int fa[200010];
int son[200010];
struct Edge{
	int v,next;
}edge[400010];
int cut,head[200010];
void add_edge(int u,int v){
	edge[++cut].v=v;
	edge[cut].next=head[u];
	head[u]=cut;
}
int dfs(int node,int nedge){
	//cerr<<node<<" "<<nedge<<"\n";
	int ans=nedge*s[node];
	if(!son[node]){
		//cerr<<ans<<"\n";
		return ans;
	}
	int give=nedge/son[node];
	int remain=nedge-give*son[node];
	vector<int>value;
	for(int i=head[node];i;i=edge[i].next){
		int v=edge[i].v;
		if(v==fa[node]){
			continue;
		}
		int ls=dfs(v,give);
		ans+=ls;
		value.push_back(ls);
	}
	priority_queue<int>q;
	if(remain){
		for(int i=head[node],j=0;i;i=edge[i].next,j++){
			int v=edge[i].v;
			int more=dfs(v,give+1)-value[j];
			q.push(more);
		}
		for(int i=1;i<=remain;i++){
			ans+=q.top();
		}
	}
	//cerr<<ans<<"\n";
	return ans;
}

signed main(){
	t=read();
	while(t--){
		//cerr<<"<\n";
		//memset(c,0,sizeof(c));
		memset(fa,0,sizeof(fa));
		memset(son,0,sizeof(son));
		memset(head,0,sizeof(head));
		cut=0;
		n=read(),k=read();
		fa[1]=1;
		for(int i=2;i<=n;i++){
			fa[i]=read();
			son[fa[i]]++;
			add_edge(i,fa[i]);
			add_edge(fa[i],i);
		}
		for(int i=1;i<=n;i++){
			s[i]=read();
		}
		print(dfs(1,k)),putchar('\n');
	}
	return 0;
}