Submission #412545

#	Time	Username	Problem	Language	Result	Execution time	Memory
412545		jeqcho	Race (IOI11_race)	C++17	43 / 100	3107 ms	150900 KiB

race

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fi first
#define se second


// subtask 1,2,3

int const n=2e5;
unordered_map<int,int> adj[n];
int sub[n];
int const INF=1e9;
int mn=INF;
int k;

int getsub(int now, int par)
{
	sub[now]=1;
	trav(chi,adj[now])
	{
		if(chi.fi==par)continue;
		sub[now]+=getsub(chi.fi,now);
	}
	return sub[now];
}

int centroid(int now, int par, int siz)
{
	trav(chi,adj[now])
	{
		if(chi.fi==par)continue;
		if(sub[chi.fi]>siz/2)return centroid(chi.fi,now,siz);
	}
	return now;
}

int const k_=1e6+3;
unordered_set<int> path[k_];
unordered_set<int> pos;
bitset<k_> got;
unordered_map<int,int>len[n];

void dfs(int now, int par, int cur, int id, int dep)
{
	if(cur>k)return;
	pos.insert(cur);
	got[cur]=1;
	path[cur].insert(id);
	if(len[id].find(cur)==len[id].end())
	{
		len[id][cur]=dep;
	}
	else
	{
		len[id][cur]=min(len[id][cur],dep);
	}
	trav(chi,adj[now])
	{
		if(chi.fi==par)continue;
		dfs(chi.fi,now,cur+chi.se,id,dep+1);
	}
}

void solve(int now)
{
	pos.clear();
	trav(chi,adj[now])
	{
		len[chi.fi].clear();
		dfs(chi.fi,now,chi.se,chi.fi,1);
	}
	pos.insert(0);
	path[0].insert(now);
	len[now][0]=0;
	trav(i,pos)
	{
		if(!got[k-i])continue;
		vpi a;
		trav(id,path[i])
		{
			a.pb({len[id][i],id});
		}
		sort(all(a));
		vpi b;
		trav(id,path[k-i])
		{
			b.pb({len[id][k-i],id});
		}
		sort(all(b));
		if(a[0].se==b[0].se)
		{
			if(sz(a)>1)
			{
				mn=min(mn,a[1].fi+b[0].fi);
			}
			if(sz(b)>1)
			{
				mn=min(mn,a[0].fi+b[1].fi);
			}
		}
		else
		{
			mn=min(mn,a[0].fi+b[0].fi);
		}
	}
	trav(e,pos)
	{
		got[e]=0;
		path[e].clear();
	}
}


void decomp(int now)
{
	int siz = getsub(now,-1);
	int u = centroid(now,-1,siz);
	solve(u);
	trav(chi,adj[u])
	{
		adj[chi.fi].erase(u);
		decomp(chi.fi);
	}
}

int best_path(int N, int K, int H[][2], int L[]){
	k=K;
	F0R(i,N-1)
	{
		int u = H[i][0];
		int v = H[i][1];
		adj[u].insert({v,L[i]});
		adj[v].insert({u,L[i]});
	}
	decomp(0);
	
	if(mn==INF)return -1;
	return mn;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 0 / 57