Submission #1068436

#	Time	Username	Problem	Language	Result	Execution time	Memory
1068436		apper	Race (IOI11_race)	C++17	21 / 100	186 ms	63572 KiB

race

#include "race.h"

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define ll long long 
#define pb push_back
using namespace std;
using namespace __gnu_pbds;
/*------------------------------------code------------------------------------*/
const ll MAXN=1e5+9;
const ll INF=1e9+9;
const ll R=(1<<18);
const int X=18;
//const ll M=1e9+7;
//const ll P=47;

int n, k;
vector<pair<int, int>> adj[MAXN];
vector<int> sz(MAXN);
vector<int> done(MAXN);
int ans=INF, curr;
vector<int> dist[10*MAXN];
vector<int> deg(MAXN);
vector<int> group(MAXN);

int dfs(int v, int p)
{
	sz[v]=1;
	for(auto [u, w] : adj[v])
	{
		if(u==p || done[u])
			continue;
		sz[v]+=dfs(u, v);
	}
	return sz[v];
}

int get(int v, int p, int mx)
{
	for(auto [u, w] : adj[v])
	{
		if(u==p || done[u])
			continue;
		if(sz[u]>mx)
			return get(u, v, mx);
	}
	return v;
}

void mark(int v, int p, ll d)
{
	dist[d].pb(v);
	group[v]=curr;
	deg[v]=deg[p]+1;
	for(auto [u, w] : adj[v])
	{
		if(u==p || done[u] || d+w>k || deg[v]>=ans)
			continue;
		mark(u, v, d+w);
	}
}

void solve(int v, int p, ll d)
{
	if(d==k)
	{
		ans=min(ans, deg[v]);
		return;
	}
	for(int u : dist[k-d])
		if(group[u]!=group[v])
			ans=min(ans, deg[v]+deg[u]);
	for(auto [u, w] : adj[v])
	{
		if(u==p || done[u] || d+w>k || deg[v]>=ans)
			continue;
		solve(u, v, d+w);
	}
}

void cls(int v, int p, ll d)
{
	group[v]=0;
	dist[d].clear();
	deg[v]=0;
	for(auto [u, w] : adj[v])
		if(group[u])
			cls(u, v, d+w);
}

void decompose(int v)
{
	int c = get(v, -1, dfs(v, -1)/2);
	done[c]=true;
	deg[c]=0;
	curr=1;
	for(auto [u, w] : adj[c])
	{
		if(done[u] || w>k)
			continue;
		mark(u, c, w);
		curr++;
	}
	for(auto [u, w] : adj[c])
	{
		if(done[u] || w>k)
			continue;
		solve(u, c, w);
	}
	
	
		
		
	for(auto [u, w] : adj[c])
		if(!done[u] && w<=k)
			cls(u, v, w);
	for(auto [u, w] : adj[c])
		if(!done[u])	
			decompose(u);
}

int best_path(int N, int K, int edges[][2], int weights[]) 
{
	if(k==1) 
		return 0;
	n=N;
	k=K;
	for(int i=0;i<n-1;i++)
	{
		int u = edges[i][0];
		int v = edges[i][1];
		adj[u].pb({v, weights[i]});
		adj[v].pb({u, weights[i]});
	}
	decompose(1);
	return (ans==INF ? -1 : ans);
}

/*
int main()
{
    cin.tie(0); ios_base::sync_with_stdio(0);
	solve();
	return 0;
}
*/

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