Submission #778792

#	Time	Username	Problem	Language	Result	Execution time	Memory
778792		MilosMilutinovic	Cyberland (APIO23_cyberland)	C++17	100 / 100	1286 ms	114252 KiB

cyberland

#include "cyberland.h"
#include <bits/stdc++.h>

using namespace std;

const double eps = 1e-7;

const int MAX = 100005;
vector<pair<int, int>> g[MAX];
double dist[MAX * 68];
double lst[MAX * 68];

double solve(int n, int m, int k, int h, std::vector<int> x, std::vector<int> y, std::vector<int> c, std::vector<int> a) {
  k = min(k, 66);
  for (int i = 0; i < n; i++) {
    g[i].clear();
  }
  for (int i = 0; i < m; i++) {
    g[x[i]].emplace_back(y[i], c[i]);
    g[y[i]].emplace_back(x[i], c[i]);
  }
  vector<int> que(1, 0);
  vector<bool> was(n, false);
  was[0] = true;
  for (int b = 0; b < (int) que.size(); b++) {
    int i = que[b];
    for (auto& p : g[i]) {
      int j = p.first;
      if (j == h) {
        was[j] = true;
      }
      if (!was[j]) {
        was[j] = true;
        que.push_back(j);
      }
    }
  }
  if (!was[h]) {
    return -1;
  }
  const double inf = 1e15;
  k += 1;
  que.push_back(h);
  for (int i : que) {
    for (int j = 0; j < k; j++) {
      dist[i * k + j] = inf;
      lst[i * k + j] = inf;
    }
  }
  priority_queue<pair<int, pair<double, int>>> pq;
  for (int j : que) {
    if (j == 0 || a[j] == 0) {
      dist[j * k] = 0;
      pq.push({0, {dist[j * k], j * k}});
    }
  }
  double ans = inf;
  while (!pq.empty()) {
    auto it = pq.top();
    int v = it.second.second;
    pq.pop();
    int i = v / k;
    int j = v % k;
    if (i == h) {
      ans = min(ans, dist[v]);
      if (ans <= eps) {
        return ans;
      }
      continue;
    }
    if (lst[v] <= dist[v] + eps) {
      continue;
    }
    lst[v] = dist[v];
    for (auto& p : g[i]) {
      int to = p.first;
      int w = p.second;
      if (to == 0 || a[to] == 0) {
        continue;
      }
      if (dist[to * k + j] > dist[v] + w + eps) {
        int nto = to * k + j;
        dist[nto] = dist[v] + w;
        pq.push({-j, {-dist[nto], nto}});
      }
      if (a[to] == 2) {
        if (j + 1 < k && dist[to * k + j + 1] > (dist[v] + w) / 2.000000 + eps) {
          int nto = to * k + j + 1;
          dist[nto] = (dist[v] + w) / 2.000000;
          pq.push({-(j + 1), {-dist[nto], nto}});
        }
      }
    }
  }
  if (ans == inf) {
    ans = -1;
  }
  return ans;
}

/*
1
3 2 30
2
1 2 1
1 2 12
2 0 4

4.00000000000

1
4 4 30
3
1 0 2 1
0 1 5
0 2 4
1 3 2
2 3 4

2.00000000000
*/

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 19 / 19
• Subtask 5: 7 / 7
• Subtask 6: 16 / 16
• Subtask 7: 29 / 29
• Subtask 8: 3 / 3