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Submission #1082977

# Submission time Handle Problem Language Result Execution time Memory
1082977 2024-09-02T09:22:48 Z avighna Aesthetic (NOI20_aesthetic) C++17
0 / 100
 2000 ms 90276 KB 
#include <bits/stdc++.h>

typedef long long ll;

struct To {
  ll v, w;
  ll i;
};

struct Edge {
  ll u, v, w;
};

const ll inf = 1e15;

int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr);

  ll n, m;
  std::cin >> n >> m;
  std::vector<std::vector<To>> adj(n + 1);
  std::vector<Edge> edges;
  for (ll i = 0, u, v, w; i < m; ++i) {
    std::cin >> u >> v >> w;
    adj[u].push_back({v, w, i});
    adj[v].push_back({u, w, i});
    edges.push_back({u, v, w});
  }

  auto sssp = [&](ll node) {
    std::vector<ll> ans(n + 1, inf);
    std::vector<bool> vis(n + 1);
    std::priority_queue<std::pair<ll, ll>> pq;
    ans[node] = 0;
    pq.push({0, node});
    while (!pq.empty()) {
      auto [d, node] = pq.top();
      d *= -1;
      pq.pop();
      if (vis[node]) {
        continue;
      }
      vis[node] = true;
      for (auto [ch, w, cur_i] : adj[node]) {
        if (ans[ch] > d + w) {
          ans[ch] = d + w;
          pq.push({-ans[ch], ch});
        }
      }
    }
    return ans;
  };

  auto sssp1 = sssp(1);
  auto ssspn = sssp(n);

  auto check = [&](ll x) {
    std::vector<std::vector<To>> new_adj(n + 1);
    for (ll i = 0; i < m; ++i) {
      auto [u, v, w] = edges[i];
      if (sssp1[u] + w + ssspn[v] <= x or sssp1[v] + w + ssspn[u] <= x) {
        new_adj[u].push_back({v, w, i});
        new_adj[v].push_back({u, w, i});
      }
    }
    std::vector<bool> is_bridge(m), vis(n + 1), enc(n + 1);
    enc[n] = true;
    std::vector<ll> low(n + 1), tin(n + 1);
    ll timer = 0;
    std::function<void(ll, ll)> dfs;
    dfs = [&](ll node, ll par) {
      if (vis[node]) {
        return;
      }
      vis[node] = true;
      tin[node] = timer++;
      low[node] = tin[node];
      for (auto &[ch, w, i] : new_adj[node]) {
        if (ch == par) {
          continue;
        }
        if (!vis[ch]) {
          dfs(ch, node);
          enc[node] = enc[node] || enc[ch];
        }
        is_bridge[i] = low[ch] > tin[node] and enc[ch];
        low[node] = std::min(low[node], low[ch]);
      }
    };
    dfs(1, 0);
    ll worst_road = edges[m - 1].w;
    for (ll i = m - 2; i >= 0; --i) {
      auto [u, v, w] = edges[i];
      if (is_bridge[i] and std::min(sssp1[u] + w + worst_road + ssspn[v],
                                    sssp1[v] + w + worst_road + ssspn[u]) > x) {
        return true;
      }
      worst_road = std::max(worst_road, edges[i].w);
    }
    return false;
  };

  ll s = sssp1[n], e = 1e10;
  while (s < e) {
    ll m = s + (e - s) / 2;
    if (check(m)) {
      s = m + 1;
    } else {
      e = m;
    }
  }
  std::cout << s << '\n';
}

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Incorrect 0 ms 348 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Incorrect 0 ms 348 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #3
0 / 7.0

# Verdict Execution time Memory Grader output
1 Incorrect 235 ms 45796 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Incorrect 253 ms 46564 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #5
0 / 16.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2080 ms 90276 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #6
0 / 22.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2080 ms 90276 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #7
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Incorrect 0 ms 348 KB Output isn't correct
4 Halted 0 ms 0 KB -