Submission #413169

#	Time	Username	Problem	Language	Result	Execution time	Memory
413169		usachevd0	Highway Tolls (IOI18_highway)	C++14	0 / 100	22 ms	712 KiB

highway

#include <bits/stdc++.h>
#ifndef LOCAL
    #include "highway.h"
#endif

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define Time (clock() * 1.0 / CLOCKS_PER_SEC)
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
using ld = long double;
template<typename T1, typename T2> bool chkmin(T1& x, T2 y) {
    return y < x ? (x = y, true) : false;
}
template<typename T1, typename T2> bool chkmax(T1& x, T2 y) {
    return y > x ? (x = y, true) : false;
}
void debug_out() {
    cerr << endl;
}
template<typename T1, typename... T2> void debug_out(T1 A, T2... B) {
    cerr << ' ' << A;
    debug_out(B...);
}
template<typename T> void mdebug_out(T* a, int n) {
    for (int i = 0; i < n; ++i)
        cerr << a[i] << ' ';
    cerr << endl;
}
#ifdef LOCAL
    #define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
    #define mdebug(a, n) cerr << #a << ": ", mdebug_out(a, n)
#else
    #define debug(...) 1337
    #define mdebug(a, n) 1337
#endif
template<typename T> ostream& operator << (ostream& stream, const vector<T>& v) {
    for (auto& x : v)
        stream << x << ' ';
    return stream;
}
template<typename T1, typename T2> ostream& operator << (ostream& stream, const pair<T1, T2>& p) {
    return stream << p.first << ' ' << p.second;
}


const int maxN = 9e4 + 4;
int col[maxN];

ll ask(const vector<int>& w);
void answer(int s, int t);
void find_pair(int n, vector<int> eu, vector<int> ev, int A, int B) {
    #ifdef LOCAL
        #define seed 228
    #else
        #define seed time(0)
    #endif
    mt19937 rng(seed);
    int m = eu.size();
    assert(A == 1 && B == 2);
    
    auto askCol = [&]() -> ll {
        vector<int> w(m);
        for (int i = 0; i < m; ++i) {
            int a = eu[i], b = ev[i];
            if (col[a] == col[b]) {
                w[i] = 1;
            } else {
                w[i] = 0;
            }
        }
        return ask(w);
    };
    
    while (true) {
        for (int v = 0; v < n; ++v)
            col[v] = rng() & 1;
        if (askCol() & 1) break;
    }
    vector<int> vtx[2];
    int ans[2];
    for (int v = 0; v < n; ++v) {
        vtx[col[v]].push_back(v);
    }
    for (int t = 0; t < 2; ++t) {
        int vl = -1;
        int vr = (int)vtx[t].size() - 1;
        while (vr - vl > 1) {
            int vm = (vl + vr) >> 1;
            for (int i = 0; i < vm; ++i)
                col[vtx[t][i]] = t ^ 1;
            for (int i = vm; i < vtx[t].size(); ++i)
                col[vtx[t][i]] = t;
            for (int v : vtx[t ^ 1])
                col[v] = t ^ 1;
            if (askCol() & 1)
                vl = vm;
            else
                vr = vm;
        }
        ans[t] = vtx[t][vr];
    }
    answer(ans[0], ans[1]);
}




#ifdef LOCAL


namespace {

constexpr int MAX_NUM_CALLS = 100;
constexpr long long INF = 1LL << 61;

int N, M, A, B, S, T;
std::vector<int> U, V;
std::vector<std::vector<std::pair<int, int>>> graph;

bool answered, wrong_pair;
int num_calls;

int read_int() {
  int x;
  if (scanf("%d", &x) != 1) {
    fprintf(stderr, "Error while reading input\n");
    exit(1);
  }
  return x;
}

void wrong_answer(const char *MSG) {
  printf("Wrong Answer: %s\n", MSG);
  exit(0);
}

}  // namespace

long long ask(const std::vector<int> &w) {
  if (++num_calls > MAX_NUM_CALLS) {
    wrong_answer("more than 100 calls to ask");
  }
  if (w.size() != (size_t)M) {
    wrong_answer("w is invalid");
  }
  for (size_t i = 0; i < w.size(); ++i) {
    if (!(w[i] == 0 || w[i] == 1)) {
      wrong_answer("w is invalid");
    }
  }

  std::vector<bool> visited(N, false);
  std::vector<long long> current_dist(N, INF);
  std::queue<int> qa, qb;
  qa.push(S);
  current_dist[S] = 0;
  while (!qa.empty() || !qb.empty()) {
    int v;
    if (qb.empty() ||
        (!qa.empty() && current_dist[qa.front()] <= current_dist[qb.front()])) {
      v = qa.front();
      qa.pop();
    } else {
      v = qb.front();
      qb.pop();
    }
    if (visited[v]) {
      continue;
    }
    visited[v] = true;
    long long d = current_dist[v];
    if (v == T) {
      return d;
    }
    for (auto e : graph[v]) {
      int vv = e.first;
      int ei = e.second;
      if (!visited[vv]) {
        if (w[ei] == 0) {
          if (current_dist[vv] > d + A) {
            current_dist[vv] = d + A;
            qa.push(vv);
          }
        } else {
          if (current_dist[vv] > d + B) {
            current_dist[vv] = d + B;
            qb.push(vv);
          }
        }
      }
    }
  }
  return -1;
}

void answer(int s, int t) {
  if (answered) {
    wrong_answer("answered not exactly once");
  }

  if (!((s == S && t == T) || (s == T && t == S))) {
    wrong_pair = true;
  }

  answered = true;
}

int main() {
freopen("in", "r", stdin);
  N = read_int();
  M = read_int();
  A = read_int();
  B = read_int();
  S = read_int();
  T = read_int();
  U.resize(M);
  V.resize(M);
  graph.assign(N, std::vector<std::pair<int, int>>());
  for (int i = 0; i < M; ++i) {
    U[i] = read_int();
    V[i] = read_int();
    graph[U[i]].push_back({V[i], i});
    graph[V[i]].push_back({U[i], i});
  }

  answered = false;
  wrong_pair = false;
  num_calls = 0;
  find_pair(N, U, V, A, B);
  if (!answered) {
    wrong_answer("answered not exactly once");
  }
  if (wrong_pair) {
    wrong_answer("{s, t} is wrong");
  }
  printf("Accepted: %d\n", num_calls);
  return 0;
}


// int32_t main() {
// #ifdef LOCAL
//     freopen("in", "r", stdin);
// #endif
//     ios::sync_with_stdio(0);
//     cin.tie(0);


//     return 0;
// }
#endif

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:101:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |             for (int i = vm; i < vtx[t].size(); ++i)
      |                              ~~^~~~~~~~~~~~~~~

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