单源最短路 Dijkstra O(mlogn) (类实现)

转载自 Felicia 的bolg
单源最短路 Dijkstra O(mlogn) (类实现)
单源最短路 Dijkstra O(mlogn) (类实现)


#include <iostream>


#include <vector>


#include <map>




#define maxn 1010


using namespace std;


typedef double weight;




class graph_c






{


public:


void init(int _n);


void dijkstra(int S);


void add_edge(int u, int v, weight w);


private:


int n;


vector <int> r[maxn];


vector <weight> e[maxn];


weight dist[maxn];


int pa[maxn];


multimap <weight, int> h;


};




void graph_c::init(int _n)






{


n = _n;


for (int i = 0; i < n; i++)






{


r[i].clear();


e[i].clear();


}


}




void graph_c::add_edge(int u, int v, weight w)






{


r[u].push_back(v);


e[u].push_back(w);


}




void graph_c::dijkstra(int S)






{


weight d, tmp;


int v;


multimap<weight, int>::iterator it;


h.clear();


for (int i = 0; i < n; i++) dist[i] = -1;


dist[S] = 0;


pa[S] = -1;


h.insert(multimap<weight, int>::value_type(0, S));


while (!h.empty())






{


it = h.begin();


v = it->second;


d = it->first;


h.erase(it);


for (int i = 0; i < r[v].size(); i++)






{


tmp = d + e[v][i];


int j = r[v][i];


if (dist[j] < 0 || tmp < dist[j])






{


dist[j] = tmp;


pa[j] = v;


h.insert(multimap<weight, int>::value_type(tmp, j));


}


}


}


}