Submission #516478

#	Time	Username	Problem	Language	Result	Execution time	Memory
516478		mars4	Race (IOI11_race)	C++17	100 / 100	1026 ms	46560 KiB

race

#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 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<pair<ll,ll>>> v;
ll k;
ll ans=inf;

class CentroidDecomposition
{
	ll N;

	void dfs_sz(vector<vector<pair<ll,ll>>> &v,ll cur,ll prev)
	{
		sz[cur]=1;
		for(auto [i,w]:v[cur])
		{
			if(i!=prev and !visited[i])
			{
				dfs_sz(v,i,cur);
				sz[cur]+=sz[i];
			}
		}
	}

	ll get_centroid(vector<vector<pair<ll,ll>>> &v,ll cur,ll prev,ll tot_sz)
	{
		for(auto [i,w]:v[cur])
		{
			if(i!=prev and !visited[i] and sz[i]>tot_sz/2)
			{
				return get_centroid(v,i,cur,tot_sz);
			}
		}
		return cur;
	}

	void calc(vector<vector<pair<ll,ll>>> &v,ll cur,ll prev,ll len,ll roads)
	{
		if(dist.count(k-len))
		{
			ans=min(ans,roads+dist[k-len]);
		}
		for(auto [i,w]:v[cur])
		{
			if(i!=prev and !visited[i])
			{
				calc(v,i,cur,len+w,roads+1);
			}
		}
	}

	void update(vector<vector<pair<ll,ll>>> &v,ll cur,ll prev,ll len,ll roads)
	{
		if(!dist.count(len))
		{
			dist[len]=roads;
		}
		else
		{
			dist[len]=min(dist[len],roads);
		}
		for(auto [i,w]:v[cur])
		{
			if(i!=prev and !visited[i])
			{
				update(v,i,cur,len+w,roads+1);
			}
		}
	}

	void build(vector<vector<pair<ll,ll>>> &v,ll cur,ll prev)
	{
		dist.clear();
		dfs_sz(v,cur,prev);
		ll centroid=get_centroid(v,cur,prev,sz[cur]);
		visited[centroid]=true;
		parent[centroid]=prev;
		dist[0]=0;
		for(auto [i,w]:v[centroid])
		{
			if(!visited[i])
			{
				calc(v,i,centroid,w,1);
				update(v,i,centroid,w,1);
			}
		}
		for(auto [i,w]:v[centroid])
		{
			if(!visited[i])
			{
				build(v,i,centroid);
			}
		}
	}

	public:
	vector<ll> parent;
	vector<ll> sz;
	map<ll,ll> dist;
	vector<bool> visited;

	void init(vector<vector<pair<ll,ll>>> &v)
	{
		N=(ll)v.size();
		parent=vector<ll>(N);
		sz=vector<ll>(N);
		visited=vector<bool>(N);
		build(v,0,-1);
	}
};

int best_path(int N,int K,int H[][2],int L[])
{
	k=K;
	v=vector<vector<pair<ll,ll>>>(N);
	ans=inf;
	forn(i,0,N-1)
	{
		ll l=H[i][0];
		ll r=H[i][1];
		ll w=L[i];
		v[l].push_back({r,w});
		v[r].push_back({l,w});
	}
	CentroidDecomposition cd;
	cd.init(v);
	if(ans==inf)
	{
		ans=-1;
	}
	return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57