warshall-floyd
(graph/warshall-floyd.hpp)

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• Last update: 2021-08-01 23:46:19+09:00
• Include: #include "graph/warshall-floyd.hpp"

Depends on

• graph/template.hpp

Verified with

• test/aoj/GRL_1_C.test.cpp

Code

#ifndef __GRAPH__WARSHALL__FLOYD
#define __GRAPH__WARSHALL__FLOYD
// @title warshall-floyd
#include "template.hpp"

#include <limits>
#include <vector>

template < typename T >
struct WarshallFloyd {
  const T INF; // dijkstraとINFの値を揃えるため、型Tの最大値の半分を使う
  const int V; // 頂点数
  Graph<T> g;
  std::vector<std::vector<T>> dist;
  WarshallFloyd(Graph<T> &g): INF(std::numeric_limits<T>::max()/2), V(g.size()), g(g), dist(V, std::vector<T>(V, INF)) { init(); }
  WarshallFloyd(Graph<T> &g, int V): INF(std::numeric_limits<T>::max()/2), V(V), g(g), dist(V, std::vector<T>(V, INF)) { init(); }
  void init() {
    for (int i = 0; i < V; ++i) {
      dist[i][i] = 0;
      for (auto &e: g[i]) dist[i][e.to] = e.cost;
    }
    for (int k = 0; k < V; ++k) {
      for (int i = 0; i < V; ++i) {
        for (int j = 0; j < V; ++j) {
          if (dist[i][k] == INF || dist[k][j] == INF) continue;
          T d = dist[i][k]+dist[k][j];
          if (dist[i][j] > d) dist[i][j] = d;
        }
      }
    }
  }
  bool has_negative_cycle() {
    for (int i = 0; i < V; ++i) {
      if (dist[i][i] < 0) return true;
    }
    return false;
  }
};

#endif // __GRAPH__WARSHALL__FLOYD

#line 1 "graph/warshall-floyd.hpp"


// @title warshall-floyd
#line 1 "graph/template.hpp"



#include <iostream>
#include <vector>

template< typename T >
struct Edge {
  int from, to;
  T cost;
  Edge() {}
  Edge(int f, int t) : from(f), to(t), cost(1) {}
  Edge(int f, int t, T c) : from(f), to(t), cost(c) {}
  friend bool operator < (const Edge& lhs, const Edge& rhs) { return lhs.cost < rhs.cost; };
  friend bool operator > (const Edge& lhs, const Edge& rhs) { return rhs < lhs; };
  friend bool operator <= (const Edge& lhs, const Edge& rhs) { return !(lhs > rhs); };
  friend bool operator >= (const Edge& lhs, const Edge& rhs) { return !(lhs < rhs); };
};

template< typename T >
using Edges = std::vector< Edge< T > >;
template< typename T >
using Graph = std::vector< Edges< T > >;

template< typename T >
void debug(Graph<T> &g, int n = -1) {
    if (n == -1) n = g.size();
    for (int i = 0; i < n; ++i) {
        std::cerr << i  << "\t";
        for (auto &e: g[i]) {
            std::cerr << e.to << ",";
        }
        std::cerr << std::endl;
    }
}


#line 5 "graph/warshall-floyd.hpp"

#include <limits>
#line 8 "graph/warshall-floyd.hpp"

template < typename T >
struct WarshallFloyd {
  const T INF; // dijkstraとINFの値を揃えるため、型Tの最大値の半分を使う
  const int V; // 頂点数
  Graph<T> g;
  std::vector<std::vector<T>> dist;
  WarshallFloyd(Graph<T> &g): INF(std::numeric_limits<T>::max()/2), V(g.size()), g(g), dist(V, std::vector<T>(V, INF)) { init(); }
  WarshallFloyd(Graph<T> &g, int V): INF(std::numeric_limits<T>::max()/2), V(V), g(g), dist(V, std::vector<T>(V, INF)) { init(); }
  void init() {
    for (int i = 0; i < V; ++i) {
      dist[i][i] = 0;
      for (auto &e: g[i]) dist[i][e.to] = e.cost;
    }
    for (int k = 0; k < V; ++k) {
      for (int i = 0; i < V; ++i) {
        for (int j = 0; j < V; ++j) {
          if (dist[i][k] == INF || dist[k][j] == INF) continue;
          T d = dist[i][k]+dist[k][j];
          if (dist[i][j] > d) dist[i][j] = d;
        }
      }
    }
  }
  bool has_negative_cycle() {
    for (int i = 0; i < V; ++i) {
      if (dist[i][i] < 0) return true;
    }
    return false;
  }
};

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