oj.uz

답안 #284441

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
284441 2020-08-27T11:41:19 Z Haunted_Cpp Islands (IOI08_islands) C++17
90 / 100
 1844 ms 131076 KB 
/**
 *  author: Haunted_Cpp
**/
 
#include <bits/stdc++.h>
using namespace std;
 
#pragma GCC optimize("Ofast")
#pragma GCC target("fma,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
 
template<typename T> ostream &operator << (ostream &os, const vector<T> &v) { os << '{'; string sep; for (const auto &x : v) os << sep << x, sep = ", "; return os << '}'; }
template<typename T, size_t size> ostream &operator << (ostream &os, const array<T, size> &arr) { os << '{'; string sep; for (const auto &x : arr) os << sep << x, sep = ", "; return os << '}'; }
template<typename A, typename B> ostream &operator << (ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
 
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << ' ' << H; debug_out(T...); }
 
#ifdef LOCAL
#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#else
#define debug(...) 47
#endif
 
typedef long long i64;
 
const int MAX_N = 1e6 + 5;
 
vector<vector<int>> g(MAX_N);
 
int Time = 0, cycle_start, cycle_end;
 
//~ vector<short> color(MAX_N); 
vector<int> nxt(MAX_N), cost(MAX_N), par(MAX_N), cycle;

bitset<MAX_N> stack_status;
bitset<MAX_N> is_done;
bitset<MAX_N> is_cycle;
bitset<MAX_N> vis;
 
void find_cycle(int node, int p) {
  stack_status[node] = 1;
  for (auto et : g[node]) {
    if (et == p && !(nxt[p] == node && nxt[node] == p)) continue;
    if (stack_status[et] == 0) {
     par[et] = node;
     find_cycle(et, node);
    } else if (!is_done[et] && stack_status[et] == 1) {
      cycle_start = et;
      cycle_end = node;
    }
  }
  is_done[node] = 1;
}
 
int root;
 
pair<i64, int> dfs(int node, int p) {
  pair<i64, int> best_way = {0, node};
  for (auto et : g[node]) {
    const int w = (nxt[node] == et ? cost[node] : cost[et]);
    if (et != root && is_cycle[et]) continue;
    if (et != p) {
      pair<i64, int> cur = dfs(et, node);
      cur.first += w;
      best_way = max(best_way, cur);
    }
  } 
  return best_way;
}
 
i64 get_depth(int node, int p) {
  i64 mx = 0;
  for (auto et : g[node]) {
    const int w = (nxt[node] == et ? cost[node] : cost[et]);
    if (is_cycle[et]) continue;
    if (et != p) {
      mx = max(mx, w + get_depth(et, node));
    }
  }
  return mx;
}
 
i64 find_cost(int node) {
  vis[node] = true;
  i64 res = 0;
  for (auto et : g[node]) {
    const int w = (nxt[node] == et ? cost[node] : cost[et]);
    if (is_cycle[node] && is_cycle[et]) {
      res += w;
    }
    if (!vis[et]) {
      vis[et] = true;
      res += find_cost(et);
    }
  }
  return res;
}
 
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0); 
  int n;
  cin >> n;
  for (int st = 0; st < n; st++) {
    int et, w;
    cin >> et >> w;
    --et;
    nxt[st] = et;
    cost[st] = w;
    g[st].emplace_back(et);
    g[et].emplace_back(st);
  }
  i64 ans = 0;
  for (int i = 0; i < n; i++) {
    if (stack_status[i] != 0) continue;
    cycle.clear();
    find_cycle(i, -1);
    for (int cur = cycle_end; cur != cycle_start; cur = par[cur]) {
      cycle.emplace_back(cur);
      is_cycle[cur] = 1;
    }
    is_cycle[cycle_start] = 1;
    cycle.emplace_back(cycle_start);
    reverse(cycle.begin(), cycle.end());
    i64 res = 0;
    for (auto to : cycle) {
      root = to;
      pair<i64, int> best_way = dfs(root, -1);
      res = max(res, dfs(best_way.second, -1).first);
    }
    i64 cycle_cost = find_cost(i) / 2;
    i64 ccw = get_depth(cycle[0], -1); 
    i64 cw = get_depth(cycle[0], -1); 
    i64 start = 0;
    debug(cycle_cost);
    for (int j = 1; j < (int) cycle.size(); j++) {
      const int st = cycle[j - 1];
      const int et = cycle[j];
      const int w = (nxt[st] == et ? cost[st] : cost[et]);
      start += w;
      res = max(res, cw + start + get_depth(et, -1));
      cw = max(cw, -start + get_depth(et, -1));
      const i64 other = cycle_cost - start;
      res = max(res, ccw + other + get_depth(et, -1));
      ccw = max(ccw, start + get_depth(et, -1));
    }
    res = max({res, cw, ccw});
    ans += res;
  }
  cout << ans << '\n';
  return 0;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:22:20: warning: statement has no effect [-Wunused-value]
   22 | #define debug(...) 47
      |                    ^~
islands.cpp:136:5: note: in expansion of macro 'debug'
  136 |     debug(cycle_cost);
      |     ^~~~~

Subtask #1
33.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 25 ms 35584 KB Output is correct
2 Correct 25 ms 35584 KB Output is correct
3 Correct 25 ms 35584 KB Output is correct
4 Correct 26 ms 35584 KB Output is correct
5 Correct 26 ms 35616 KB Output is correct
6 Correct 26 ms 35740 KB Output is correct
7 Correct 25 ms 35584 KB Output is correct
8 Correct 26 ms 35640 KB Output is correct
9 Correct 26 ms 35576 KB Output is correct
10 Correct 26 ms 35584 KB Output is correct
11 Correct 25 ms 35584 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 26 ms 35704 KB Output is correct
2 Correct 26 ms 35656 KB Output is correct

Subtask #3
4.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 26 ms 35704 KB Output is correct
2 Correct 27 ms 35960 KB Output is correct

Subtask #4
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 35 ms 36352 KB Output is correct
2 Correct 48 ms 38368 KB Output is correct
3 Correct 38 ms 36344 KB Output is correct
4 Correct 31 ms 36096 KB Output is correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 54 ms 39288 KB Output is correct
2 Correct 66 ms 40824 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 129 ms 44408 KB Output is correct
2 Correct 129 ms 50556 KB Output is correct
3 Correct 157 ms 59040 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 191 ms 50168 KB Output is correct
2 Correct 244 ms 71508 KB Output is correct
3 Correct 279 ms 80584 KB Output is correct
4 Correct 353 ms 94776 KB Output is correct

Subtask #8
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 374 ms 71392 KB Output is correct
2 Correct 1194 ms 117240 KB Output is correct
3 Correct 339 ms 62968 KB Output is correct
4 Correct 469 ms 97988 KB Output is correct
5 Correct 464 ms 97776 KB Output is correct
6 Correct 1844 ms 67228 KB Output is correct
7 Correct 499 ms 130336 KB Output is correct

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 419 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -