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답안 #548122

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
548122 2022-04-12T13:39:54 Z lorenzoferrari Islands (IOI08_islands) C++17
0 / 100
 2000 ms 131072 KB 
#include <bits/stdc++.h>
using namespace std;
using LL = long long;

#define watch(x) cerr << (#x) << " is " << x << endl

vector<bool> vis, cycle;
vector<array<LL, 2>> prv, nxt;
vector<LL> dl, dr;
vector<LL> f;

LL max_path(const vector<int>& c, const vector<vector<array<LL, 3>>>& adj) {
  auto find_cycle = [&](auto&& self, int v, int pid = -1) -> bool {
    if (vis[v]) return cycle[v] = true;
    vis[v] = true;
    for (auto [u, w, eid] : adj[v]) {
      if (eid == pid) continue;
      bool works = self(self, u, v);
      if (works) {
        nxt[v] = {u, w};
        prv[u] = {v, w};
        return cycle[v] ? false : cycle[v] = true;
      }
    }
    return false;
  };
  find_cycle(find_cycle, c[0]);
  LL dep = 0;
  auto path_in_tree = [&](auto&& self, int v, int p = -1) -> LL {
    while (dep++ >= 1e7) ;
    LL ans = 0;
    for (auto [u, w, eid] : adj[v]) {
      if (u == p || u == prv[v][0] || u == nxt[v][0]) continue;
      ans = max(ans, w + self(self, u, v));
    }
    return ans;
  };
  int start = -1;
  for (int i : c) {
    if (cycle[i]) {
      start = i;
      f[i] = path_in_tree(path_in_tree, i);
    }
  }
  return 42;
  // multiset<LL> L, R;
  // {
  //   int v = start;
  //   int u = start;
  //   dl[v] = dr[u] = 0;
  //   do {
  //     auto [nv, lw] = nxt[v];
  //     auto [nu, rw] = prv[u];
  //     if (v != start) L.insert(f[v] + dl[v]);
  //     if (u != start) R.insert(f[u] + dr[u]);
  //     if (nv != start) dl[nv] = dl[v] + lw;
  //     dr[nu] = dr[u] + rw;
  //     v = nv;
  //     u = nu;
  //   } while (v != start);
  // }
  // assert(dl[start] == 0);
  // LL len = dr[start];
  // LL bias = 0;
  // LL ans = 0;
  // {
  //   int v = start;
  //   do {
  //     // watch(v);
  //     // watch(bias);
  //     // cerr << "L: "; for (LL i : L) cerr << i << " "; cerr << endl;
  //     // cerr << "R: "; for (LL i : R) cerr << i << " "; cerr << endl;
  //     // cerr << endl;
  //     ans = max(ans, *prev(L.end()) - bias + f[v]);
  //     ans = max(ans, *prev(R.end()) + bias + f[v]);
  //     int nv = nxt[v][0];
  //     if (nv == start) break;
  //     bias += nxt[v][1];
  //     L.insert(f[v] + dl[v] + len);
  //     R.insert(f[v] + dr[v] - len);
  //     if (L.count(f[nv] + dl[nv])) L.erase(L.find(f[nv] + dl[nv]));
  //     if (R.count(f[nv] + dr[nv])) R.erase(R.find(f[nv] + dr[nv]));
  //     v = nv;
  //   } while (v != start);
  // }
  // return ans;
}

int main() {
#ifdef LORENZO
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  int n; cin >> n;
  vector<vector<array<LL, 3>>> adj(n);
  for (int i = 0; i < n; ++i) {
    int a; cin >> a; --a;
    int w; cin >> w;
    adj[i].push_back({a, w, i});
    adj[a].push_back({i, w, i});
  }
  vis.assign(n, false);
  vector<vector<int>> cc;
  auto dfs = [&](auto&& self, int v) -> void {
    vis[v] = true;
    cc.back().push_back(v);
    for (auto [u, _, __] : adj[v]) {
      if (!vis[u]) {
        self(self, u);
      }
    }
  };
  for (int i = 0; i < n; ++i) {
    if (!vis[i]) {
      cc.push_back(vector<int>(0));
      dfs(dfs, i);
    }
  }
  f.assign(n, 0);
  dl.assign(n, 1e18);
  dr.assign(n, 1e18);
  prv.assign(n, {-1,-1});
  nxt.assign(n, {-1,-1});
  vis.assign(n, false);
  cycle.assign(n, false);
  LL ans = 0;
  for (const auto& c : cc) {
    ans += max_path(c, adj);
  }
  cout << ans << "\n";
}

Compilation message

islands.cpp: In function 'LL max_path(const std::vector<int>&, const std::vector<std::vector<std::array<long long int, 3> > >&)':
islands.cpp:38:7: warning: variable 'start' set but not used [-Wunused-but-set-variable]
   38 |   int start = -1;
      |       ^~~~~

Subtask #1
0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 0 ms 212 KB Output isn't correct
2 Execution timed out 2086 ms 106432 KB Time limit exceeded
3 Incorrect 1 ms 340 KB Output isn't correct
4 Incorrect 0 ms 212 KB Output isn't correct
5 Incorrect 0 ms 212 KB Output isn't correct
6 Incorrect 0 ms 212 KB Output isn't correct
7 Incorrect 0 ms 212 KB Output isn't correct
8 Runtime error 85 ms 131072 KB Execution killed with signal 9
9 Incorrect 0 ms 212 KB Output isn't correct
10 Incorrect 1 ms 212 KB Output isn't correct
11 Incorrect 1 ms 212 KB Output isn't correct

Subtask #2
0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 121 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #3
0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 77 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #4
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2075 ms 104500 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 272 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #6
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 599 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 334 ms 60884 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 893 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 820 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -