D. Captain Flint and Treasure

Posted 2021-11-12 thusloop

Captain Flint and Treasure
思路：子树中为正的留着（入队列），负的舍去（最后输出，入栈）

#pragma GCC optimize(2)
#pragma GCC optimize(3,"Ofast","inline")
#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define pii pair<int,int>
#define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
const int maxn=2e5+100;
ll a[maxn],b[maxn],mx[maxn];
int ans[maxn];
vector<int>g[maxn];
stack<int>s;
queue<int>q;
void dfs(int x,int f)
{
	for(auto it:g[x])
	{
		if(it==f)continue;
		dfs(it,x);
		if(mx[it]>=0)
		{
			q.push(it);
			mx[x]+=mx[it];
		}
	}
	if(mx[x]<0)
	{
		s.push(x);
	}
	else if(f==-1)
	{
		s.push(x);
	}
}
signed main()
{
	IOS
	int n;
	cin>>n;
	for(int i=1; i<=n; i++)
	{
		cin>>a[i];
		mx[i]=a[i];
	}
	for(int i=1; i<=n; i++)
	{
		cin>>b[i];
		if(b[i]==-1)continue;
		g[b[i]].pb(i);
		//g[i].pb(b[i]);
	}
	for(int i=1; i<=n; i++)
	{
		if(b[i]==-1)
		{
			dfs(i,-1);
		}
	}
	int cnt=0;
	while(!q.empty())
	{
		int tp=q.front();
		q.pop();
		ans[++cnt]=tp; 
	}
	while(!s.empty())
	{
		int tp=s.top();
		s.pop();
		ans[++cnt]=tp;
	}
	ll res=0;
	for(int i=1; i<=cnt; i++)
	{
		int it=ans[i];
		res+=a[it];
		if(b[it]==-1)continue;
		a[b[it]]+=a[it];
	}
	cout<<res<<"\\n";
	for(int i=1; i<=cnt; i++)
	{
		cout<<ans[i]<<" ";
	}
}