Submission #836253

#	Time	Username	Problem	Language	Result	Execution time	Memory
836253		mousebeaver	Highway Tolls (IOI18_highway)	C++14	12 / 100	114 ms	11856 KiB

highway

#define ll long long
#define pll pair<ll, ll>
#include "highway.h"
#include <bits/stdc++.h>
using namespace std;

void dfs(vector<vector<pll>>& adjlist, vector<ll>& depth, vector<int>& upedge, int i)
{
    for(pll p : adjlist[i])
    {
        if(depth[p.first] == -1)
        {
            depth[p.first] = depth[i]+1;
            upedge[p.first] = p.second;
            dfs(adjlist, depth, upedge, p.first);
        }
    }
}

void find_pair(int n, std::vector<int> u, std::vector<int> v, int a, int b) 
{
    vector<vector<pll>> adjlist(n, vector<pll> (0));
    for(ll i = 0; i < n-1; i++)
    {
        adjlist[u[i]].push_back({v[i], i});
        adjlist[v[i]].push_back({u[i], i});
    }

    vector<ll> depth(n, -1);
    depth[0] = 0;
    vector<int> upedge(n, -1);
    dfs(adjlist, depth, upedge, 0);

    vector<int> w(n-1, 0);
    ll dist = ask(w)/a;
    vector<ll> c(0);
    for(ll i = 0; i < n; i++)
    {
        if(depth[i] == dist)
        {
            c.push_back(i);
        }
    }

    while(c.size() > 1)
    {
        int mid = (c.size())/2;
        w.assign(n-1, 0);
        for(int i = mid; i < (int) c.size(); i++)
        {
            w[upedge[c[i]]] = 1;
        }

        if(ask(w) > dist*a)
        {
            vector<ll> s(0);
            for(int i = mid; i < (int) c.size(); i++)
            {
                s.push_back(c[i]);
            }
            c = s;
        }
        else
        {
            vector<ll> s(0);
            for(int i = 0; i < mid; i++)
            {
                s.push_back(c[i]);
            }
            c = s;
        }
    }
    answer(0, c[0]);
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31