Submission #130541

#	Time	Username	Problem	Language	Result	Execution time	Memory
130541		groeneprof	Highway Tolls (IOI18_highway)	C++14	12 / 100	305 ms	262148 KiB

highway

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

struct edge{
	int id, v;
};

int N, M, A, B;
vector<vector<edge> > graph;

void dfs(int u, int par, int id, int d, int dist, vector<int>& idlist, vector<int>& vlist){
	if(d == dist){
		idlist.push_back(id);
		vlist.push_back(u);
	}
	for(edge e : graph[u]) if(e.v!=par){
		dfs(e.v, u, e.id, d+1, dist, idlist, vlist);
	}
}

int findT(int S, int par, int dist, int id){
	vector<int> idlist, vlist;
	dfs(S, par, id, 0, dist, idlist, vlist);
	int L = 0, R = idlist.size();
	while(L!=R-1){
		int Mi = (L+R)/2;
		vector<signed> w(M, 0);
		for(int i = 0; i<Mi; i++){
			w[idlist[i]]=1;
		}
		if(ask(w)==dist*A){
			L = Mi;
		}
		else{
			R = Mi;
		}
	}
	return vlist[L];
}

void find_pair(signed _N, vector<signed> U, vector<signed> V, signed _A, signed _B) {
	N = _N;
	M = U.size();
	A = _A;
	B = _B;
	graph.resize(N);
	for(int i = 0; i<M; i++){
		graph[U[i]].push_back({i, V[i]});
		graph[V[i]].push_back({i, U[i]});
	}
	vector<signed> w(M, 0);
	int dist = ask(w)/A;
	answer(0, findT(0, 0, dist, -1));
}

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