Submission #838138

#	Time	Username	Problem	Language	Result	Execution time	Memory
838138		becaido	통행료 (IOI18_highway)	C++17	100 / 100	192 ms	12152 KiB

highway

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include <bits/stdc++.h>
using namespace std;

#ifndef WAIMAI
#include "highway.h"
#endif

#ifdef WAIMAI
#define debug(HEHE...) cout << "[" << #HEHE << "] : ", dout(HEHE)
void dout() { cout << "\n"; }
template<typename T, typename...U>
void dout(T t, U...u) { cout << t << (sizeof...(u) ? ", " : ""), dout(u...); }
#else
#define debug(...) 7122
#endif

#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for(int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second

#ifdef WAIMAI
ll ask(const vector<int> &w);
void answer(int s, int t);
#endif

const int SIZE = 1.3e5 + 5;

ll len;
vector<pair<int, int>> adj[SIZE], all[2];
vector<int> e;
int g[SIZE];
bool is[SIZE];

int cal(int s, int M) {
    int sz = all[s].size();
    int l = 0, r = sz - 1;
    while (l < r) {
        int mid = (l + r) / 2;
        FOR (i, 0, M - 1) e[i] = !is[i];
        FOR (i, mid + 1, sz - 1) e[all[s][i].S] = 1;
        if (ask(e) == len) r = mid;
        else l = mid + 1;
    }
    return all[s][l].F;
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
    int M = U.size();
    e.resize(M, 0);
    FOR (i, 0, M - 1) {
        adj[U[i]].pb(V[i], i);
        adj[V[i]].pb(U[i], i);
    }

    len = ask(e);
    int l = 0, r = M - 1;
    while (l < r) {
        int mid = (l + r) / 2;
        fill(e.begin(), e.end(), 0);
        fill(e.begin(), e.begin() + mid + 1, 1);
        if (ask(e) == len) l = mid + 1;
        else r = mid;
    }

    queue<int> q;
    is[l] = 1;
    fill(g, g + N, -1);
    q.push(U[l]), g[U[l]] = 0, all[0].pb(U[l], -1);
    q.push(V[l]), g[V[l]] = 1, all[1].pb(V[l], -1);
    while (q.size()) {
        int pos = q.front();
        q.pop();
        for (auto [np, id] : adj[pos]) if (g[np] == -1) {
            g[np] = g[pos];
            is[id] = 1;
            all[g[pos]].pb(np, id);
            q.push(np);
        }
    }

    answer(cal(0, M), cal(1, M));
}

/*
in1
4 4
1 3 1 3
0 1
0 2
0 3
1 2
out1
1 3
*/

#ifdef WAIMAI
namespace {

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

int N, M, A, B, S, T;
vector<int> U, V;
vector<vector<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

ll ask(const 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");
    }
  }

  vector<bool> visited(N, false);
  vector<ll> current_dist(N, INF);
  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;
    ll 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() {
  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, vector<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;
}
#endif

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