Submission #778027

#	Time	Username	Problem	Language	Result	Execution time	Memory
778027		mars4	Valley (BOI19_valley)	C++17	100 / 100	173 ms	33272 KiB

valley

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> 

using namespace std;
using namespace __gnu_pbds; 

#define ff              first
#define ss              second
#define ll              int64_t
#define ld              long double
#define nl              cout<<"\n"
#define i128            __int128_t
#define all(v)          v.begin(),v.end()
#define mset(a,v)       memset((a),(v),sizeof(a))
#define forn(i,a,b)     for(int64_t i=int64_t(a);i<int64_t(b);++i)
#define forb(i,a,b)     for(int64_t i=int64_t(a);i>=int64_t(b);--i)
#define fastio()        ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);

#define mod         1'000'000'007
#define mod2        998'244'353 
#define inf         1'000'000'000'000'007
#define pi          3.14159265358979323846

template<class key,class cmp=std::less<key>>
using ordered_set=tree<key,null_type,cmp,rb_tree_tag,tree_order_statistics_node_update>;

template<class L,class R> ostream& operator<<(ostream& out,pair<L,R> &p)        {return out<<"("<<p.ff<<", "<<p.ss<<")";}
template<class T> ostream& operator<<(ostream& out,vector<T> &v)                {out<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())out<<", ";out<<*it;}return out<<"]";}
template<class T> ostream& operator<<(ostream& out,deque<T> &v)                 {out<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())out<<", ";out<<*it;}return out<<"]";}
template<class T> ostream& operator<<(ostream& out,set<T> &s)                   {out<<"{";for(auto it=s.begin();it!=s.end();++it){if(it!=s.begin())out<<", ";out<<*it;}return out<<"}";}
template<class T> ostream& operator<<(ostream& out,ordered_set<T> &s)           {out<<"{";for(auto it=s.begin();it!=s.end();++it){if(it!=s.begin())out<<", ";out<<*it;}return out<<"}";}
template<class L,class R> ostream& operator<<(ostream& out,map<L,R> &m)         {out<<"{";for(auto it=m.begin();it!=m.end();++it){if(it!=m.begin())out<<", ";out<<*it;}return out<<"}";}

void dbg_out() {cerr<<"]\n";}
template<typename Head,typename... Tail> 
void dbg_out(Head H,Tail... T) {cerr<<H;if(sizeof...(Tail))cerr<<", ";dbg_out(T...);}
#ifdef LOCAL
#define dbg(...) cerr<<"["<<#__VA_ARGS__<<"] = [",dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

//---------------------------------mars4---------------------------------

vector<vector<ll>> v;
vector<vector<pair<ll,ll>>> g;
vector<ll> dist;

void dfs(ll cur,ll prev)
{
	for(auto [nxt,w]:g[cur])
	{
		if(nxt!=prev)
		{
			dist[nxt]=dist[cur]+w;
			dfs(nxt,cur);
		}
	}
}

class SegtreeMin
{
	ll N;
	
	public:
	vector<ll> segtree;

	void init(ll n,ll val=0)
	{
		N=n;
		segtree=vector<ll>(N<<1,val);
	}

	void build(vector<ll> &a)
	{
		forn(i,0,N)
			segtree[i+N]=a[i];
		forb(i,N-1,1)
			segtree[i]=min(segtree[i<<1],segtree[i<<1|1]);
	}

	void update(ll i,ll val)
	{
		if(segtree[i+N]>val)
		{
			for(segtree[i+=N]=val;i>>=1;)
				segtree[i]=min(segtree[i<<1],segtree[i<<1|1]);
		}
	}

	ll query(ll l,ll r)
	{
		ll res=2*inf;
		for(l+=N,r+=N+1;l<r;l>>=1,r>>=1)
		{
			if(l&1) res=min(res,segtree[l++]);
			if(r&1) res=min(res,segtree[--r]);
		}
		return res;
	}
};

class HLD
{
	ll N;
	ll timer;

	void dfs_sz(ll cur,ll prev,vector<vector<ll>> &v)
	{
		child[cur]=1;
		parent[cur]=prev;
		for(ll i:v[cur])
		{
			if(i!=prev)
			{
				depth[i]=depth[cur]+1;
				dfs_sz(i,cur,v);
				child[cur]+=child[i];
			}
		}
	}

	void dfs_hld(ll cur,ll prev,ll top,vector<vector<ll>> &v)
	{
		timer++;
		st[cur]=timer;
		tp[cur]=top;
		dn[top]=cur;
		ll h_ind=-1,h_sz=-1;
		for(ll i=0;i<(ll)v[cur].size();i++)
		{
			if(v[cur][i]!=prev)
			{
				if(child[v[cur][i]]>h_sz)
				{
					h_ind=i;
					h_sz=child[v[cur][i]];
				}
			}
		}
		if(h_ind==-1)
		{
			ed[cur]=timer;
			return;
		}
		swap(v[cur][0],v[cur][h_ind]);
		dfs_hld(v[cur][0],cur,top,v);
		for(ll i:v[cur])
		{
			if(i!=prev and i!=v[cur][0])
			{
				dfs_hld(i,cur,i,v);
			}
		}
		ed[cur]=timer;
	}

	public:
	vector<ll> child;
	vector<ll> parent;
	vector<ll> depth;
	vector<ll> st;
	vector<ll> ed;
	vector<ll> tp;
	vector<ll> dn;

	// use segtree class
	SegtreeMin s_down;
	SegtreeMin s_up;

	void init(vector<vector<ll>> &v,ll root=0)
	{
		N=(ll)v.size();
		s_down.init(N,2*inf);
		s_up.init(N,2*inf);
		child=vector<ll>(N);
		parent=vector<ll>(N);
		depth=vector<ll>(N);
		st=vector<ll>(N);
		ed=vector<ll>(N);
		tp=vector<ll>(N);
		dn=vector<ll>(N);
		timer=-1;
		dfs_sz(root,root,v);
		dfs_hld(root,root,root,v);
	}

	void update(ll node)
	{
		ll cur=node;
		while(true)
		{
			s_down.update(st[cur],dist[node]);
			s_up.update(st[cur],dist[node]-2*dist[cur]);
			ll ncur=parent[tp[cur]];
			if(cur==ncur)
			{
				break;
			}
			cur=ncur;
		}
	}

	// use appropriate query operation (vertex/edge)
	ll query(ll node,ll cut)
	{
		ll cur=node;
		ll res=inf;
		while(depth[tp[cur]]>depth[cut])
		{
			ll up_val=s_up.query(st[tp[cur]],st[cur])+dist[node];
			ll down_val=s_down.query(st[cur],st[dn[tp[cur]]])+dist[node]-2*dist[cur];
			res=min({res,up_val,down_val});
			cur=parent[tp[cur]];
		}
		ll up_val=s_up.query(st[cut],st[cur])+dist[node];
		ll down_val=s_down.query(st[cur],st[dn[tp[cur]]])+dist[node]-2*dist[cur];
		res=min({res,up_val,down_val});
		return res;
	}
};

int main()
{
	fastio();
	ll z,n,m,t,k,i,j,l,d,h,r;
	ll q,root;
	cin>>n>>m>>q>>root;
	root--;
	v=vector<vector<ll>>(n);
	g=vector<vector<pair<ll,ll>>>(n);
	dist=vector<ll>(n);
	vector<pair<ll,ll>> edges(n-1);
	forn(i,0,n-1)
	{
		cin>>l>>r>>d;
		l--,r--;
		v[l].push_back(r);
		v[r].push_back(l);
		g[l].push_back({r,d});
		g[r].push_back({l,d});
		edges[i]={l,r};
	}
	dfs(root,-1);
	HLD hld;
	hld.init(v,root);
	forn(i,0,m)
	{
		cin>>d;
		hld.update(d-1);
	}
	forn(i,0,q)
	{
		cin>>k>>d;
		k--,d--;
		auto [l,r]=edges[k];
		if(hld.depth[l]<hld.depth[r])
		{
			swap(l,r);
		}
		if(hld.st[l]<=hld.st[d] and hld.ed[l]>=hld.st[d])
		{
			ll res=hld.query(d,l);
			if(res==inf)
			{
				cout<<"oo\n";
			}
			else
			{
				cout<<res<<"\n";
			}
		}
		else
		{
			cout<<"escaped\n";
		}
	}
	cerr<<"\nTime elapsed: "<<1000*clock()/CLOCKS_PER_SEC<<"ms\n";
	return 0;
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:227:5: warning: unused variable 'z' [-Wunused-variable]
  227 |  ll z,n,m,t,k,i,j,l,d,h,r;
      |     ^
valley.cpp:227:11: warning: unused variable 't' [-Wunused-variable]
  227 |  ll z,n,m,t,k,i,j,l,d,h,r;
      |           ^
valley.cpp:227:15: warning: unused variable 'i' [-Wunused-variable]
  227 |  ll z,n,m,t,k,i,j,l,d,h,r;
      |               ^
valley.cpp:227:17: warning: unused variable 'j' [-Wunused-variable]
  227 |  ll z,n,m,t,k,i,j,l,d,h,r;
      |                 ^
valley.cpp:227:23: warning: unused variable 'h' [-Wunused-variable]
  227 |  ll z,n,m,t,k,i,j,l,d,h,r;
      |                       ^

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41