Submission #1021926

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021926		fv3	Highway Tolls (IOI18_highway)	C++14	12 / 100	77 ms	8100 KiB

highway

#include <bits/stdc++.h>	
#include "highway.h"
 
using namespace std;
typedef long long ll;

int edgeCnt;
vector<vector<pair<int, int>>> adj;

int bfs_dist;
vector<pair<int, int>> sus_edges;
void find_sus_edges(int index, int last, int dist)
{
	dist += 1;

	for (auto node : adj[index])
	{
		if (node.first == last) continue;
		if (dist == bfs_dist)
			sus_edges.push_back(node);
		else
			find_sus_edges(node.first, index, dist);
	}
}

int find_T(int root, ll dist)
{
	find_sus_edges(root, root, 0);

	int l = 0, r = sus_edges.size() - 1;
	while (l < r)
	{
		int c = (l + r + 1) / 2;

		vector<int> w(edgeCnt);
		for (int i = c; i <= r; i++)
			w[sus_edges[i].second] = 1;

		ll cur_dist = ask(w);
		if (cur_dist == dist)
			r = c - 1;
		else
			l = c;
	}

	return sus_edges[l].first;
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) 
{
	edgeCnt = U.size();
	adj = vector<vector<pair<int, int>>>(N);
	for (int i = 0; i < edgeCnt; i++)
	{
		adj[U[i]].push_back({V[i], i});
		adj[V[i]].push_back({U[i], i});
	}

	int S = 0;
	ll dist = ask(vector<int>(edgeCnt));
	bfs_dist = dist / A;

	int T = find_T(S, dist);

	//cerr << "Guess: S = " << S << ", T = " << T << '\n';

	answer(S, T);
}

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