Submission #1046248

#	Time	Username	Problem	Language	Result	Execution time	Memory
1046248		I_FloPPed21	Race (IOI11_race)	C++14	0 / 100	3 ms	21848 KiB

race

#include "race.h"
#include <bits/stdc++.h>

using namespace std;
map<int,long long> mp[200005] ;
vector<pair<int,int>> adj[200005];
int h[200005][2], target = 0,sum[200005],height[200005],ans = 1e9,n,k;

void precomp(int nod, int p, int hd)
{
    height[nod] = hd ;
    for ( auto u : adj[nod] )
    {
        if ( u.first != p )
        {
            sum[u.first] += sum[nod]    + u.second;
            precomp(u.first,nod,hd + 1);
        }
    }
}

void small(int nod,int p )
{
    mp[nod][sum[nod]] = height[nod];
    long long real_target = target + 2 * sum[nod];
    for ( auto u : adj[nod] )
    {
        if ( u.first != p )
        {
            small(u.first,nod);
        }
    }

    for ( auto u : adj[nod] )
    {
        if( u.first != p )
        {
            if( mp[u.first].size() > mp[nod].size())
                swap(mp[nod],mp[u.first]);

            for ( auto k : mp[u.first] )
            {
                long long real = real_target - k.first ;

                /* if( nod == 6 && u.first == 8 )
                 {
                     cout << real << '\n';
                 }*/
                if ( mp[nod].find(real) != mp[nod].end())
                {
                    //cout << nod << " " << u.first << " " << k.first << " " << k.second << '\n';
                    ans = min ( long(ans), long(k.second + mp[nod][real] - 2 * height[nod]));
                }


            }

            for ( auto k : mp[u.first])
            {
                if( mp[nod][k.first] == 0 )
                    mp[nod][k.first] = k .second;
                else
                    mp[nod][k.first] = min(mp[nod][k.first],k.second);

            }
        }
    }

    /*if( nod == 6)
    {
        cout << mp[nod][real_target]<< '\n';
    }*/
}
int best_path(int n, int k, int h[][2], int costs [] )
{
    if( k == 1 )
    {
        return 0 ;
    }
    target =k ;

    for ( int i = 1; i < n ; i ++ )
    {
        adj[h[i][1]].push_back({h[i][0],costs[i]});
        adj[h[i][0]].push_back({h[i][1],costs[i]});
    }


    precomp(0,-1,1);
    small(0,-1);
    return ans == (long long)1e9 ? -1:ans;
}
int v[200005];
/*int main()
{
   cin >> n >> k;
   for ( int i = 1; i < n ; i ++ )
   {
       cin >> h[i][0] >> h[i][1] >> v[i] ;
   }

   cout << best_path(n,k,h,v);

   return 0;
}*/

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