제출 #775421

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
775421		Alihan_8	통행료 (IOI18_highway)	C++17	5 / 100	109 ms	16776 KiB

highway

#ifndef EVAL
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <utility>
#include <vector>
//#include "highway.h"

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;
}
#endif // EVAL

#include <bits/stdc++.h>

#include "highway.h"

using namespace std;

#define all(x) x.begin(), x.end()
#define pb push_back
#define ln '\n'
//#define int long long

template <class _T>
bool chmin(_T &x, const _T &y){
    bool flag = false;
    if ( x > y ){
        x = y; flag |= true;
    }
    return flag;
}

template <class _T>
bool chmax(_T &x, const _T &y){
    bool flag = false;
    if ( x < y ){
        x = y; flag |= true;
    }
    return flag;
}


void find_pair(int n, vector<int> U, vector<int> V, int A, int B) {
    int m = (int)U.size();
    assert(m == n - 1);
    vector <pair<int,int>> g[n], edge(m);
    vector <int> tree;
    for ( int i = 0; i < m; i++ ){
        g[U[i]].pb({V[i], i});
        g[V[i]].pb({U[i], i});
    }
    function <void(int,int)> dfs = [&](int x, int par){
        for ( auto [to, id]: g[x] ){
            if ( to == par ){
                continue;
            } tree.pb(id);
            edge[id] = {x, to};
            dfs(to, x);
        }
    };
    int dis = ask(vector <int> (m, 0)) / A * B;
    auto get = [&](int root){
        tree.clear();
        dfs(root, -1);
        int l = 0, r = m - 1;
        while ( l < r ){
            int md = (l + r) >> 1;
            vector <int> f(m, 0);
            for ( int i = 0; i <= md; i++ ){
                f[tree[i]] = 1;
            }
            if ( ask(f) == dis ) r = md;
            else l = md + 1;
        }
        return edge[tree[l]].second;
    };
    int s = get(0), t = get(s);
    answer(s, t);
}

#ifndef EVAL
/*
4 4 1 3
0 1
0 2
0 3
1 2

1 3

7 6 1 2
0 1
0 2
1 3
1 4
2 5
4 6

3 2
*/
int main() {
  N = read_int();
  M = read_int();
  A = read_int();
  B = 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});
  }
  S = read_int();
  T = read_int();

  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;
}

#endif // EVAL

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