Submission #807618

#	Time	Username	Problem	Language	Result	Execution time	Memory
807618		Lobo	Highway Tolls (IOI18_highway)	C++17	51 / 100	191 ms	15452 KiB

highway

#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define all(x) x.begin(),x.end()
#define int long long
const int inf = 1e18+10;
const int maxn = 9e4+10;

int n, m, par[maxn], parid[maxn];
vector<int> g[maxn];

void find_pair(int32_t N, std::vector<int32_t> U, std::vector<int32_t> V, int32_t A, int32_t B) {
	// int M = U.size();
	// for (int j = 0; j < 50; ++j) {
	//   std::vector<int> w(M);
	//   for (int i = 0; i < M; ++i) {
	//     w[i] = 0;
	//   }
	//   long long toll = ask(w);
	// }
	// answer(0, N - 1);


	n = N;
	m = U.size();
	for(int i = 0; i < m; i++) {
		g[U[i]].pb(i);
		g[V[i]].pb(i);
	}
	vector<int32_t> vectudoa(m,0);
	int tudoa = ask(vectudoa);
	int path = tudoa/A;

	int edgein = -1;
	int lbs,rbs;
	vector<int32_t> vectoll(m,0);
	lbs = 0;
	rbs = m-1;
	while(lbs <= rbs) {
		int mid = (lbs+rbs)/2;
		vectoll.clear(); vectoll.resize(m,0);
		for(int i = 0; i <= mid; i++) {
			vectoll[i] = 1;
		}

		int toll = ask(vectoll);

		if(toll != tudoa) {
			edgein = mid;
			rbs = mid-1;
		}
		else {
			lbs = mid+1;
		}
	}

	assert(edgein != -1);

	int ss = U[edgein];
	int tt = V[edgein];

	vector<pair<int,int>> d(n+10,mp(inf,0));
	d[ss] = mp(0,ss); par[ss] = -1; parid[ss] = -1;
	d[tt] = mp(0,tt); par[tt] = -1; parid[tt] = -1;

	queue<int> q; q.push(ss); q.push(tt);
	while(q.size()) {
		int u = q.front(); q.pop();

		for(auto id : g[u]) {
			int v = U[id]+V[id]-u;
			if(d[v].fr > d[u].fr+1) {
				d[v] = mp(d[u].fr+1,d[u].sc);
				par[v] = u;
				parid[v] = id;
				q.push(v);
			}
		}
	}

	vector<pair<int,int>> Ds;
	for(int i = 0; i < n; i++) {
		if(d[i].sc == ss) {
			Ds.pb(mp(d[i].fr,i));
		}
	}
	sort(all(Ds));
	lbs = 0;
	rbs = (int) Ds.size()-1;
	int32_t s = -1;
	while(lbs <= rbs) {
		int mid = (lbs+rbs)/2;

		vectoll.clear(); vectoll.resize(m,0);

		for(int i = 0; i <= mid; i++) {
			if(parid[Ds[i].sc] != -1) vectoll[parid[Ds[i].sc]] = 0;
		}

		for(int i = mid+1; i < (int) Ds.size(); i++) {
			if(parid[Ds[i].sc] != -1) vectoll[parid[Ds[i].sc]] = 1;
		}

		int toll = ask(vectoll);

		if(toll == tudoa) {
			s = Ds[mid].sc;
			rbs = mid-1;
		}
		else {
			lbs = mid+1;
		}
	}

	vector<pair<int,int>> Dt;
	for(int i = 0; i < n; i++) {
		if(d[i].sc == tt) {
			Dt.pb(mp(d[i].fr,i));
		}
	}
	sort(all(Dt));
	lbs = 0;
	rbs = (int) Dt.size()-1;
	int32_t t = -1;
	while(lbs <= rbs) {
		int mid = (lbs+rbs)/2;

		vectoll.clear(); vectoll.resize(m,0);

		for(int i = 0; i <= mid; i++) {
			if(parid[Dt[i].sc] != -1) vectoll[parid[Dt[i].sc]] = 0;
		}

		for(int i = mid+1; i < (int) Dt.size(); i++) {
			if(parid[Dt[i].sc] != -1) vectoll[parid[Dt[i].sc]] = 1;
		}

		int toll = ask(vectoll);

		if(toll == tudoa) {
			t = Dt[mid].sc;
			rbs = mid-1;
		}
		else {
			lbs = mid+1;
		}
	}

	// cout << ss << " " << tt << endl;
	// cout << s << " " << t << endl;
	answer(s,t);
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int32_t, std::vector<int>, std::vector<int>, int32_t, int32_t)':
highway.cpp:36:6: warning: unused variable 'path' [-Wunused-variable]
   36 |  int path = tudoa/A;
      |      ^~~~

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