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Submission #259594

# Submission time Handle Problem Language Result Execution time Memory
259594 2020-08-08T03:35:38 Z EntityIT Beads and wires (APIO14_beads) C++14
100 / 100
 367 ms 44912 KB 
#include <bits/stdc++.h>
using namespace std;

#define ALL(x) (x).begin(), (x).end()
#define SZ(x) static_cast<int>((x).size())

template<class T, size_t D>
struct vec : vector<vec<T, D - 1>> {
  template<class... Args>
  vec(size_t n = 0, Args... args)
      : vector<vec<T, D - 1>>(n, vec<T, D - 1>(args...)) {}
};
template<class T>
struct vec<T, 1> : vector<T> {
  template<class... Args>
  vec(Args... args)
      : vector<T>(args...) {}
};

template<class T>
inline bool Minimize(T& a, const T& b) { return a > b ? a = b, true : false; }
template<class T>
inline bool Maximize(T& a, const T& b) { return a < b ? a = b, true : false; }
inline int Next(int i, int n) { return i == n - 1 ? 0 : i + 1; }
inline int Prev(int i, int n) { return !i ? n - 1 : i - 1; }

mt19937 rng(static_cast<uint32_t>(chrono::steady_clock::now().time_since_epoch().count()));

int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);

  int n_vertices; cin >> n_vertices;
  vec<pair<int, int>, 2> edges_vertices(n_vertices);
  for (int i = 1; i < n_vertices; ++i) {
    int u, v, w; cin >> u >> v >> w; --u; --v;
    edges_vertices[u].emplace_back(v, w);
    edges_vertices[v].emplace_back(u, w);
  }

  vec<int, 2> down(n_vertices, 2);
  vec<array<int, 2>, 1> max_changes_vertices(n_vertices);
  function<void(int, int, int)> Down = [&](int u, int parent, int parent_edge) {
    max_changes_vertices[u][0] = max_changes_vertices[u][1] = numeric_limits<int>::min();
    for (auto& edge : edges_vertices[u]) {
      int v, w; tie(v, w) = edge;
      if (v == parent) {
        continue;
      }
      Down(v, u, w);
      down[u][0] += max(down[v][0], down[v][1]);
      int change = - max(down[v][0], down[v][1]) + w + down[v][0];
      for (int i = 0; i < SZ(max_changes_vertices[u]); ++i) {
        if (change > max_changes_vertices[u][i]) {
          swap(change, max_changes_vertices[u][i]);
        }
      }
    }
    down[u][1] = max_changes_vertices[u][0] != numeric_limits<int>::min() && parent_edge != numeric_limits<int>::min() ? down[u][0] + max_changes_vertices[u][0] + parent_edge : numeric_limits<int>::min();
  };
  Down(0, -1, numeric_limits<int>::min());

  vec<int, 2> up(n_vertices, 2);
  up[0][1] = numeric_limits<int>::min();
  function<void(int, int, int)> Up = [&](int u, int parent, int parent_edge) {
    for (auto& edge : edges_vertices[u]) {
      int v, w; tie(v, w) = edge;
      if (v == parent) {
        continue;
      }

      up[v][0] = max(up[u][0], up[u][1]) + down[u][0] - max(down[v][0], down[v][1]);
      up[v][1] = numeric_limits<int>::min();
      if (parent_edge != numeric_limits<int>::min()) {
        Maximize(up[v][1], up[v][0] - max(up[u][0], up[u][1]) + parent_edge + w + up[u][0]);
      }
      int change = - max(down[v][0], down[v][1]) + w + down[v][0];
      if (max_changes_vertices[u][0] == change) {
        if (max_changes_vertices[u][1] != numeric_limits<int>::min()) {
          Maximize(up[v][1], up[v][0] + max_changes_vertices[u][1] + w);
        }
      } else {
        if (max_changes_vertices[u][0] != numeric_limits<int>::min()) {
          Maximize(up[v][1], up[v][0] + max_changes_vertices[u][0] + w);
        }
      }

      Up(v, u, w);
    }
  };
  Up(0, -1, numeric_limits<int>::min());

  int answer = 0;
  for (int u = 0; u < n_vertices; ++u) {
    Maximize(answer, down[u][0] + max(up[u][0], up[u][1]));
    if (down[u][1] != numeric_limits<int>::min()) {
      Maximize(answer, down[u][1] + up[u][0]);
    }
  }

  cout << answer << '\n';

  return 0;
}

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 0 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 0 ms 384 KB Output is correct
8 Correct 0 ms 384 KB Output is correct
9 Correct 0 ms 384 KB Output is correct
10 Correct 1 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 384 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 0 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 0 ms 384 KB Output is correct
8 Correct 0 ms 384 KB Output is correct
9 Correct 0 ms 384 KB Output is correct
10 Correct 1 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 384 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 0 ms 384 KB Output is correct
15 Correct 0 ms 384 KB Output is correct
16 Correct 1 ms 384 KB Output is correct
17 Correct 1 ms 384 KB Output is correct
18 Correct 0 ms 384 KB Output is correct
19 Correct 0 ms 384 KB Output is correct
20 Correct 0 ms 384 KB Output is correct
21 Correct 1 ms 384 KB Output is correct
22 Correct 0 ms 384 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 0 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 0 ms 384 KB Output is correct
8 Correct 0 ms 384 KB Output is correct
9 Correct 0 ms 384 KB Output is correct
10 Correct 1 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 384 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 0 ms 384 KB Output is correct
15 Correct 0 ms 384 KB Output is correct
16 Correct 1 ms 384 KB Output is correct
17 Correct 1 ms 384 KB Output is correct
18 Correct 0 ms 384 KB Output is correct
19 Correct 0 ms 384 KB Output is correct
20 Correct 0 ms 384 KB Output is correct
21 Correct 1 ms 384 KB Output is correct
22 Correct 0 ms 384 KB Output is correct
23 Correct 4 ms 1280 KB Output is correct
24 Correct 4 ms 1280 KB Output is correct
25 Correct 4 ms 1280 KB Output is correct
26 Correct 8 ms 2304 KB Output is correct
27 Correct 8 ms 2304 KB Output is correct
28 Correct 11 ms 2304 KB Output is correct
29 Correct 7 ms 2304 KB Output is correct
30 Correct 7 ms 2304 KB Output is correct
31 Correct 10 ms 2816 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 0 ms 384 KB Output is correct
3 Correct 0 ms 384 KB Output is correct
4 Correct 0 ms 384 KB Output is correct
5 Correct 0 ms 384 KB Output is correct
6 Correct 0 ms 384 KB Output is correct
7 Correct 0 ms 384 KB Output is correct
8 Correct 0 ms 384 KB Output is correct
9 Correct 0 ms 384 KB Output is correct
10 Correct 1 ms 384 KB Output is correct
11 Correct 0 ms 384 KB Output is correct
12 Correct 0 ms 384 KB Output is correct
13 Correct 0 ms 384 KB Output is correct
14 Correct 0 ms 384 KB Output is correct
15 Correct 0 ms 384 KB Output is correct
16 Correct 1 ms 384 KB Output is correct
17 Correct 1 ms 384 KB Output is correct
18 Correct 0 ms 384 KB Output is correct
19 Correct 0 ms 384 KB Output is correct
20 Correct 0 ms 384 KB Output is correct
21 Correct 1 ms 384 KB Output is correct
22 Correct 0 ms 384 KB Output is correct
23 Correct 4 ms 1280 KB Output is correct
24 Correct 4 ms 1280 KB Output is correct
25 Correct 4 ms 1280 KB Output is correct
26 Correct 8 ms 2304 KB Output is correct
27 Correct 8 ms 2304 KB Output is correct
28 Correct 11 ms 2304 KB Output is correct
29 Correct 7 ms 2304 KB Output is correct
30 Correct 7 ms 2304 KB Output is correct
31 Correct 10 ms 2816 KB Output is correct
32 Correct 50 ms 9976 KB Output is correct
33 Correct 50 ms 9976 KB Output is correct
34 Correct 48 ms 9976 KB Output is correct
35 Correct 367 ms 39660 KB Output is correct
36 Correct 285 ms 39544 KB Output is correct
37 Correct 293 ms 39524 KB Output is correct
38 Correct 234 ms 39912 KB Output is correct
39 Correct 220 ms 39900 KB Output is correct
40 Correct 238 ms 39904 KB Output is correct
41 Correct 291 ms 44912 KB Output is correct