Submission #892390

#	Time	Username	Problem	Language	Result	Execution time	Memory
892390		d4xn	Cyberland (APIO23_cyberland)	C++17	44 / 100	46 ms	20684 KiB

cyberland

#include "cyberland.h"
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ld long double

const int N = 1e5+5;

int n, h;
ld mn[N], dis[3][N];
vector<int> arr;
vector<pair<int, ld>> adj[N];

void dijkstra(int x, int idx) {
    priority_queue<pair<ld, int>> pq;
    if (idx == 2) {
      for (int i = 1; i < n-1; i++) {
        if (arr[i]) continue;
        pq.push(make_pair(-0, i));
      }
    }
    else {
      pq.push(make_pair(-0, x));
    }

    while (!pq.empty()) {
      ld d = -pq.top().first;
      int y = pq.top().second;
      pq.pop();

      if (dis[idx][y] != -1) continue;
      dis[idx][y] = d;

      if (!idx && y == h) continue;
      for (auto& [z, d2] : adj[y]) {
        if (dis[idx][z] != -1) continue;
        pq.push(make_pair(-(d+d2), z));
      }
    }
}

double solve(int N, int m, int k, int H, vector<int> x, vector<int> y, vector<int> c, vector<int> ARR) {
    n = N;
    h = H;
    arr = ARR;
    for (int i = 0; i < n; i++) {
      adj[i].clear();
    }
    
    for (int i = 0; i < m; i++) {
        adj[x[i]].push_back(make_pair(y[i], c[i]));
        adj[y[i]].push_back(make_pair(x[i], c[i]));
    }

    for (int i = 0; i < n; i++) {
        dis[0][i] = dis[1][i] = -1;

        mn[i] = -1;
        for (auto& [j, d] : adj[i]) {
          if (j == h) continue;
          
          if (mn[i] == -1) mn[i] = d;
          else mn[i] = min(mn[i], d);
        }
    }
    dijkstra(0, 0);
    dijkstra(h, 1);
    dijkstra(-1, 2);

    // nada
    ld ans = dis[0][h];
    
    // solo 0
    for (int i = 0; i < n; i++) {
      if (arr[i] || dis[0][i] == -1 || dis[1][i] == -1) continue;
 
      ans = min(ans, dis[1][i]);
    }

    // solo 2
    for (int i = 1; i < n-1; i++) {
      if (arr[i] != 2 || dis[0][i] == -1 || dis[1][i] == -1) continue;

      ld x = dis[0][i] / 2;

      int cnt = k-1;
      while (cnt) {
        ld nwX = (x + mn[i]) / 2;
        
        if (nwX >= x) break;
        x = nwX;

        cnt--;
      }

      ans = min(ans, x + dis[1][i]);
    }
    
    // 0 y 2
    for (int i = 1; i < n-1; i++) {
      if (arr[i] != 2 || dis[0][i] == -1 || dis[1][i] == -1 || dis[2][i] == -1) continue;

      ld x = dis[2][i] / 2;

      int cnt = k-1;
      while (cnt) {
        ld nwX = (x + mn[i]) / 2;
        
        if (nwX >= x) break;
        x = nwX;

        cnt--;
      }

      ans = min(ans, x + dis[1][i]);
    }
    return ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 0 / 19
• Subtask 5: 7 / 7
• Subtask 6: 16 / 16
• Subtask 7: 0 / 29
• Subtask 8: 0 / 3