Submission #1107502

#	Time	Username	Problem	Language	Result	Execution time	Memory
1107502		thieunguyenhuy	Highway Tolls (IOI18_highway)	C++17	51 / 100	169 ms	31840 KiB

highway

#ifndef hwe
	#include "highway.h"
#endif
 
#include <bits/stdc++.h>
using namespace std;
 
#define popcount(n) (__builtin_popcountll((n)))
#define clz(n) (__builtin_clzll((n)))
#define ctz(n) (__builtin_ctzll((n)))
#define lg(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
 
#define Int __int128
#define fi first
#define se second
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
 
template <class T1, class T2>
bool maximize(T1 &x, T2 y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
template <class T1, class T2>
bool minimize(T1 &x, T2 y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
 
template <class T>
void remove_duplicate(vector<T> &ve) {
    sort (ve.begin(), ve.end());
    ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
 
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
template <class T> T random(T l, T r) {
    return uniform_int_distribution<T>(l, r)(rng);
}
template <class T> T random(T r) {
    return rng() % r;
}
 
const int N = 90000 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const ll INF = 1e18;
 
const int LIGHT = 0, HEAVY = 1;
 
int asked = 0, dist[2][N], edge[N], ver[N], dep[N];
vii adj[N];
vector<int> ve[N];
map<vector<int>, ll> mem;

#ifdef hwe
namespace Grader {
	int n, m, s, t;
	ll dist[N];
	int trace[N];
	pii edges[N];
	vii adj[N];
	vector<int> w;
 
	void get() {
		cin >> n >> m >> s >> t;
	
		for (int i = 0; i < n; ++i) adj[i].clear();

		for (int i = 0; i < m; ++i) {
			int u, v; cin >> u >> v;
			adj[u].emplace_back(v, i), adj[v].emplace_back(u, i);
			edges[i] = make_pair(u, v);
		}
	}
 
	void rand() {
		n = random(7, 7), m = random(n - 1, 15), s = random(n), t = random(n);
		while (s == t) t = random(n);
		for (int i = 1; i < n; ++i) {
			edges[i - 1] = make_pair(random(i), i);
		}
		for (int i = n - 1; i < m; ++i) {
			edges[i] = make_pair(random(n), random(n));
		}
		for (int i = 0; i < n; ++i) adj[i].clear();
		for (int i = 0; i < m; ++i) {
			int u, v; tie(u, v) = edges[i];
			adj[u].emplace_back(v, i), adj[v].emplace_back(u, i);
		}
	}
 
	void show() {
		cerr << n << ' ' << m << ' ' << s << ' ' << t << '\n';
		for (int i = 0; i < m; ++i) cerr << edges[i].fi << ' ' << edges[i].se << '\n';
	}
 
	ll dijkstra(int s, int t) {
		memset(dist, 0x0f, sizeof dist); dist[s] = 0;
		priority_queue<pli, vli, greater<pli>> pq; pq.emplace(0, s);
		while (!pq.empty()) {
			int u = pq.top().se; pq.pop();
			// cerr << "dijkstra " << u << ' ' << dist[u] << '\n';
			for (auto [v, id] : adj[u]) if (minimize(dist[v], dist[u] + w[id])) {
				trace[v] = id;
				pq.emplace(dist[v], v);
			}
		}
		int ma = -1; for (auto &x : w) maximize(ma, x);
		if (ma <= 1) cerr << "kq " << dist[t] << '\n';
		return dist[t];
	}

	void Trace() {
		cerr << "trace "; int v = t;
		while (true) {
			cerr << trace[v] << ' ';
			v = edges[trace[v]].fi ^ edges[trace[v]].se ^ v;
			if (v == s) break;
		}
	}
 
	ll ask(const vector<int> &_w) {
		w = _w; for (auto &x : w) ++x;
		return dijkstra(s, t);
	}
}
 
ll ask(const vector<int> &w) {
	return Grader::ask(w);
}
 
void answer(int s, int t) {
	cerr << "Answer " << s << ' ' << t << '\n';
	pii ans = make_pair(Grader::s, Grader::t);
	if (make_pair(s, t) != ans && make_pair(t, s) != ans) {
		cerr << "Wrong Answer\n";
		exit(0);
	}
}
#endif
 
ll myask(const vector<int> &w) {
	auto it = mem.find(w);
	if (it != mem.end()) return it->se;
	assert(++asked <= 50);
	return mem[w] = ask(w);
}
 
void bfs(const int type, int root) {
	memset(dist[type], -1, sizeof dist[type]); dist[type][root] = 0;
	queue<int> q; q.emplace(root);
	while (!q.empty()) {
		int u = q.front(); q.pop();
		for (auto [v, id] : adj[u]) if (dist[type][v] == -1) {
			dist[type][v] = dist[type][u] + 1;
			q.emplace(v);
		}
	}
}

void print(vector<int> &ve) {
	for (auto &x : ve) cerr << x << ' ';
	cerr << '\n';
}
 
void find_pair(int n, vector<int> U, vector<int> V, int A, int B) {
	int m = U.size(); asked = 0;
	for (int i = 0; i < n; ++i) adj[i].clear();
	for (int i = 0; i < m; ++i) {
		adj[U[i]].emplace_back(V[i], i), adj[V[i]].emplace_back(U[i], i);
	}
 
	vector<int> w(m, LIGHT); mem.clear();
	ll fixed = myask(w);

	int low = 0, high = m - 1, edgeId = -1;
	while (low <= high) {
		int mid = low + high >> 1; vector<int> w(m, LIGHT);
		for (int i = 0; i <= mid; ++i) w[i] = HEAVY;
		if (myask(w) != fixed) high = (edgeId = mid) - 1;
		else low = mid + 1;
	}
	int u = U[edgeId], v = V[edgeId];

	// cerr << "EdgeId " << edgeId << '\n';
	
	bfs(0, u), bfs(1, v); vector<int> S, T;
	for (int i = 0; i < n; ++i) {
		if (dist[0][i] < dist[1][i]) S.emplace_back(i);
		else if (dist[0][i] > dist[1][i]) T.emplace_back(i);
	}

	// cerr << "S: "; print(S);
	// cerr << "T: "; print(T);

	// for (auto &x : S) cerr << e[x] << ' ';
	// cerr << '\n';
	// for (auto &x : T) cerr << e[x] << ' ';
	// cerr << '\n';

	auto work = [&](const int type, const int root) {
		queue<int> q; memset(dep, -1, sizeof dep);
		q.emplace(root), dep[root] = 0; int cnt = 0;
		for (int i = 0; i < m; ++i) edge[i] = -1, ver[i] = -1;
		while (!q.empty()) {
			int u = q.front(); q.pop();
			for (auto [v, id] : adj[u]) {
				if (dist[type][v] < dist[!type][v]) {
					if (dep[v] == -1) {
						dep[v] = dep[u] + 1;
						ver[cnt] = v, edge[id] = cnt++;
						q.emplace(v);
					}
					else if (dep[v] == dep[u] + 1) {
						edge[id] = inf;
					}
				}
				else if (id != edgeId) edge[id] = inf;
			}
		}

		auto check = [&](int mid) {
			vector<int> w(m, HEAVY);
			for (int i = 0; i < m; ++i) w[i] = edge[i] >= mid;
			// cerr << "check " << myask(w) << ' ' << 1ll * numEdges * A + 1ll * (1 + dist[type][ve[mid]]) * (B - A) << '\n';
			return myask(w) != fixed;
		};

		// for (int i = 0; i < ve.size(); ++i) cerr << check(i);
		// cerr << '\n';
		// for (int i = 0; i < cnt; ++i) cerr << check(i);
		// cerr << '\n';

		int low = 0, high = cnt - 1, id = -1;
		while (low <= high) {
			int mid = low + high >> 1; 
			// if (mid == 1) cerr << "myask = " << myask(w) << '\n';
			// if (type == 0) cerr << mid << ' ' << myask(w) << '\n';
			if (check(mid)) low = (id = mid) + 1;
			else high = mid - 1;
		}
		// cerr << "id = " << id << '\n';
		return (id == -1 ? root : ver[id]);
	};

	int s = work(0, u), t = work(1, v);
	answer(s, t);
}
 
#ifdef hwe
signed main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
 
    #ifdef hwe
        freopen("input.inp", "r", stdin);
        freopen("output.out", "w", stdout);
    #else
        #define taskname ""
        if (fopen(taskname".inp", "r")) {
            freopen(taskname".inp", "r", stdin);
            freopen(taskname".out", "w", stdout);
        }
    #endif
 
    for (int _ = 0; _ < 1000; ++_) {
	    Grader::rand(); Grader::show();
	    int n = Grader::n; vector<int> U, V;
	    for (int i = 0; i < Grader::m; ++i) {
	    	int u, v; tie(u, v) = Grader::edges[i];
	    	U.emplace_back(u), V.emplace_back(v);
	    }
	    find_pair(n, U, V, 1, 2);    	
    }

    Grader::get(); Grader::show();
    int n = Grader::n; vector<int> U, V;
    for (int i = 0; i < Grader::m; ++i) {
    	int u, v; tie(u, v) = Grader::edges[i];
    	U.emplace_back(u), V.emplace_back(v);
    }
    find_pair(n, U, V, 1, 2);
 
    cerr << '\n'; return 0;
}
#endif

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:200:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  200 |   int mid = low + high >> 1; vector<int> w(m, LIGHT);
      |             ~~~~^~~~~~
highway.cpp: In lambda function:
highway.cpp:258:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  258 |    int mid = low + high >> 1;
      |              ~~~~^~~~~~

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