Submission #1318376

#	Time	Username	Problem	Language	Result	Execution time	Memory
1318376		ayaz	Dreaming (IOI13_dreaming)	C++20	0 / 100	1095 ms	11360 KiB

dreaming

#include "bits/stdc++.h"
#include <algorithm>
#include "dreaming.h"

using namespace std;

vector<vector<array<int, 2>>> g;
vector<bool> used;
vector<int> dis, nodes, path;
int n;
void dfs(int u, bool collect = 0, int p = -1) {
  if (collect) {
    nodes.push_back(u);
  }
  for (auto &[v, w] : g[u]) {
    if (v == p) continue;
    dis[v] = dis[u] + w;
    dfs(v, collect, u);
  }
}
array<int, 2> findCenter(int u) {
  nodes.clear();
  dis[u] = 0;
  dfs(u, 1);
  int ans = 1e9, cent;
  for (auto &v : nodes) {
    dis[v] = 0;
    dfs(v);
    int dist = 0;
    for (auto &z : nodes) dist = max(dist, dis[z]);
    if (ans >= dist) {
      cent = v;
      ans = dist;
    }
    used[v] = 1;
  }
  return {ans, cent};
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  int m = M, l = L;
  n = N;
  dis.resize(n + 1, 0);
  g.resize(n + 1);
  used.assign(n + 1, false);
  for (int i = 0; i < m; i++) {
    int u = A[i], v = B[i], w = T[i];
    u++, v++;
    g[u].push_back({v, w});
    g[v].push_back({u, w});
  }
  vector<array<int, 2>> mx;
  for (int u = 1; u <= n; u++) {
    if (used[u]) continue;
    mx.push_back(findCenter(u));
  }
  sort(mx.rbegin(), mx.rend());
  for (int i = 1; i < size(mx); i++) {
    g[mx[i][1]].push_back({mx[0][1], l});
    g[mx[0][1]].push_back({mx[i][1], l});
  }
  int ans = 0;
  for (int u = 1; u <= n; u++) {
    dis[u] = 0;
    dfs(u);
    ans = max(ans, *max_element(dis.begin() + 1, dis.end()));
  }
  if (m == n - 2) assert(mx[0][0] + mx[1][0] + l < ans);
  return ans;
  // if (int(mx.size()) <= 2) return mx[0] + mx[1] + l;
  // return max(mx[1] + mx[2] + 2 * l, mx[0] + mx[1] + l);
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23