Submission #255913

#	Time	Username	Problem	Language	Result	Execution time	Memory
255913		KoD	철인 이종 경기 (APIO18_duathlon)	C++17	23 / 100	189 ms	18476 KiB

count_triplets

#line 1 "main.cpp"

/**
 * @title Template
 */

#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>

#line 2 "/Users/kodamankod/Desktop/Programming/Library/other/chmin_chmax.cpp"

template <class T, class U>
constexpr bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) { 
    lhs = rhs; 
    return true; 
  }
  return false;
}

template <class T, class U>
constexpr bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) { 
    lhs = rhs; 
    return true; 
  }
  return false;
}

/**
 * @title Chmin/Chmax
 */
#line 2 "/Users/kodamankod/Desktop/Programming/Library/other/range.cpp"

#line 4 "/Users/kodamankod/Desktop/Programming/Library/other/range.cpp"

class range {
public:
  class iterator {
  private:
    int64_t M_position;

  public:
    constexpr iterator(int64_t position) noexcept: M_position(position) { }
    constexpr void operator ++ () noexcept { ++M_position; }
    constexpr bool operator != (iterator other) const noexcept { return M_position != other.M_position; }
    constexpr int64_t operator * () const noexcept { return M_position; }

  };

  class reverse_iterator {
  private:
    int64_t M_position;
  
  public:
    constexpr reverse_iterator(int64_t position) noexcept: M_position(position) { }
    constexpr void operator ++ () noexcept { --M_position; }
    constexpr bool operator != (reverse_iterator other) const noexcept { return M_position != other.M_position; }
    constexpr int64_t operator * () const noexcept { return M_position; }

  };
  
private:
  const iterator M_first, M_last;

public:
  constexpr range(int64_t first, int64_t last) noexcept: M_first(first), M_last(std::max(first, last)) { }
  constexpr iterator begin() const noexcept { return M_first; }
  constexpr iterator end() const noexcept { return M_last; }
  constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(*M_last - 1); } 
  constexpr reverse_iterator rend() const noexcept { return reverse_iterator(*M_first - 1); } 

};

/**
 * @title Range
 */
#line 2 "/Users/kodamankod/Desktop/Programming/Library/other/rev.cpp"

#include <type_traits>
#include <iterator>
#line 6 "/Users/kodamankod/Desktop/Programming/Library/other/rev.cpp"

template <class T>
class rev_impl {
public:
  using iterator = typename std::decay<T>::type::reverse_iterator;

private:
  const iterator M_begin;
  const iterator M_end;

public:
  constexpr rev_impl(T &&cont) noexcept: M_begin(std::rbegin(cont)), M_end(std::rend(cont)) { }
  constexpr iterator begin() const noexcept { return M_begin; }
  constexpr iterator end() const noexcept { return M_end; }

};

template <class T>
constexpr decltype(auto) rev(T &&cont) {
  return rev_impl<T>(std::forward<T>(cont));
}

/**
 * @title Reverser
 */
#line 2 "/Users/kodamankod/Desktop/Programming/Library/other/fix_point.cpp"

#line 4 "/Users/kodamankod/Desktop/Programming/Library/other/fix_point.cpp"

template <class Func>
struct fix_point: private Func {
  explicit constexpr fix_point(Func &&func): Func(std::forward<Func>(func)) { }
  template <class... Args>
  constexpr decltype(auto) operator () (Args &&... args) const {
    return Func::operator()(*this, std::forward<Args>(args)...);
  }
};

template <class Func>
constexpr decltype(auto) make_fix_point(Func &&func) {
  return fix_point<Func>(std::forward<Func>(func));
}

/**
 * @title Lambda Recursion
 */
#line 17 "main.cpp"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;

constexpr i32 inf32 = (i32(1) << 30) - 1;
constexpr i64 inf64 = (i64(1) << 62) - 1;

int main() {
  i32 N, M;
  std::cin >> N >> M;
  std::vector<std::vector<i32>> graph(N);
  for (auto i: range(0, M)) {
    i32 u, v;
    std::cin >> u >> v;
    --u; --v;
    graph[u].push_back(v);
    graph[v].push_back(u);
  }
  std::vector<std::vector<i32>> count(N);
  for (auto i: range(0, N)) {
    count[i].resize(graph[i].size());
  }
  std::vector<bool> visited(N);
  i64 ans = 0;
  for (auto root: range(0, N)) {
    if (visited[root]) {
      continue;
    }
    i32 size = fix_point([&](auto dfs, i32 u) -> i32 {
      visited[u] = true;
      i32 res = 1;
      for (auto i: range(0, graph[u].size())) {
        i32 v = graph[u][i];
        if (visited[v]) {
          continue;
        }
        count[u][i] = dfs(v);
        res += count[u][i];
      }
      return res;
    })(root);
    fix_point([&](auto dfs, i32 u, i32 up) -> void {
      for (auto i: range(0, graph[u].size())) {
        if (count[u][i] == 0) {
          count[u][i] = up;
        }
        else {
          dfs(graph[u][i], size - count[u][i]);
        }
      }
      for (auto x: count[u]) {
        ans += (i64) x * (size - x - 1);
      }
    })(root, 0);
  }
  std::cout << ans << '\n';
  return 0;
}

Compilation message (stderr)

main.cpp: In function 'int main()':
main.cpp:30:13: warning: unused variable 'i' [-Wunused-variable]

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