Submission #598380

#	Time	Username	Problem	Language	Result	Execution time	Memory
598380		ono_de206	Race (IOI11_race)	C++14	100 / 100	589 ms	32452 KiB

race

#include "race.h"
 
 
#include<bits/stdc++.h>
using namespace std;
 
#define pb push_back
#define ff first
#define ss second
#define in insert
 
const int mxn=2e5+10,mxk=1e6+10;
vector<pair<int,int> > g[mxn];
int global_answer=-1,n,k,vis[mxn],sub[mxn],nxt,mx;
int book_keeping,minimum_paths[mxk],achievable[mxk];
 
void dfs(int to,int fr)
{
	sub[to]=1;
	for(auto &x : g[to])
	{
		if(x.ff==fr || vis[x.ff]) continue;
		dfs(x.ff,to);
		sub[to]+=sub[x.ff];
	}
}
 
void get_cen(int to,int fr,int sz)
{
	int lomx=sz-sub[to];
	for(auto &x : g[to])
	{
		if(x.ff==fr || vis[x.ff]) continue;
		get_cen(x.ff,to,sz);
		lomx=max(lomx,sub[x.ff]);
	}
	if(lomx<mx)
	{
		mx=lomx;
		nxt=to;
	}
}

void dfs2(int to,int fr,int current_cost,int current_length,int fill)
{
	if(current_cost>k) return;
	if (!fill)
	{
    	if (achievable[k - current_cost] == book_keeping)
     	 	if (current_length + minimum_paths[k - current_cost] < global_answer || global_answer == -1)
        		global_answer = current_length + minimum_paths[k - current_cost];
 
    if (current_cost == k)
      if (current_length < global_answer || global_answer == -1)
        global_answer = current_length;
  }
  else
  {
    if (achievable[current_cost] < book_keeping)
    {
      achievable[current_cost] = book_keeping;
      minimum_paths[current_cost] = current_length;
    }
    else if (current_length < minimum_paths[current_cost])
   	{
    	  achievable[current_cost] = book_keeping;
    	  minimum_paths[current_cost] = current_length;
    	}
  	}
	for(auto &x : g[to])
	{
		if(x.ff==fr || vis[x.ff]) continue;
		dfs2(x.ff,to,current_cost+x.ss,current_length+1,fill);
	}
}
 
void solve(int id)
{
	dfs(id,-1);
	if(sub[id]<=1) return;
	mx=sub[id];
	get_cen(id,-1,sub[id]);
	id=nxt;
	book_keeping++;
	for(auto &x : g[id])
	{
		if(vis[x.ff]) continue;
		dfs2(x.ff,id,x.ss,1,0);
		dfs2(x.ff,id,x.ss,1,1);
	}
	vis[id]=1;
	for(auto &x : g[id])
	{
		if(vis[x.ff]) continue;
		solve(x.ff);
	}
}
 
int best_path(int N, int K, int h[][2], int l[])
{
	n=N;
	k=K;
	memset(vis,0,sizeof(vis));
	for(int i=0; i<N-1; i++)
	{
		g[h[i][0]].pb({h[i][1],l[i]});
		g[h[i][1]].pb({h[i][0],l[i]});
	}
	solve(0);
	return global_answer;
}

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