Submission #728415

#	Time	Username	Problem	Language	Result	Execution time	Memory
728415		NeroZein	Dreaming (IOI13_dreaming)	C++17	100 / 100	110 ms	24396 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
 
using namespace std; 
 
const int NN = 100005;
 
int a[NN], b[NN], t[NN];
vector<pair<int, int>> g[NN]; 
int vis[NN]; 
int mx[NN], mx2[NN]; 
int far[NN];
int mn[NN]; 
 
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  int n, m, l;
  n = N, m = M, l = L; 
  for (int i = 0; i < m; ++i) {
    a[i] = A[i];
    b[i] = B[i];
    t[i] = T[i];
  }
  for (int i = 0; i < m; ++i) { 
    g[a[i]].emplace_back(b[i], t[i]);
    g[b[i]].emplace_back(a[i], t[i]); 
  }
  int ncc = 0; 
  vector<int> d(n + 1); 
  int mxd = 0;
  function<void(int, int)> Dfs = [&](int v, int p) {
    vis[v] = ncc; 
    for (auto [u, w] : g[v]) {
      if (u != p) {
        Dfs(u, v); 
        mx2[v] = max(mx2[v], mx[u] + w); 
        if (mx2[v] > mx[v]) {
          swap(mx2[v], mx[v]); 
        }
      }
    }
    d[ncc] = max(d[ncc], mx[v] + mx2[v]); 
    mxd = max(mxd, d[ncc]);
  };
  for (int i = 1; i <= n + 1; ++i) mn[i] = INT_MAX;
  function<void(int, int, int)> Dfs2 = [&](int v, int p, int up) {
    far[v] = max(mx[v], up); 
    mn[ncc] = min(mn[ncc], far[v]); 
    for (auto [u, w] : g[v]) {
      if (u == p) continue; 
      int nup = max(up, mx[v] == mx[u] + w ? mx2[v] : mx[v]) + w; 
      Dfs2(u, v, nup); 
    }
  };
  for (int i = 0; i < n; ++i) {
    if (!vis[i]) {
      ncc++; 
      Dfs(i, i); 
      Dfs2(i, i, 0); 
    }
  }
  sort(mn + 1, mn + 1 + ncc, greater<int>()); 
  int ans = max({mxd, l + mn[1] + mn[2], mn[2] + mn[3] + l + l});
  if (ncc >= 2) ans = max(ans, mn[1] + mn[2] + l); 
  if (ncc >= 3) ans = max(ans, mn[2] + mn[3] + 2 * l); 
  return ans; 
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23