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Minimum spanning tree
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//Prim - Minimum spanning tree | |
#include<iostream> | |
#include<algorithm> | |
#include<functional> | |
#include<set> | |
#include<vector> | |
#include<queue> | |
#include<cstring> | |
using namespace std; | |
const int MAX_POINT_NUMBER=100000; | |
const int MAX_EDGE_NUMBER=10000000; | |
class edge | |
{ | |
public: | |
int dest,ori; | |
int length; | |
int id; | |
}; | |
bool operator< (const edge &a,const edge &b) | |
{ | |
return a.length>b.length; | |
} | |
vector<edge>g[MAX_POINT_NUMBER]; | |
priority_queue<edge>GraphSet; | |
bool usedEdgeId[MAX_EDGE_NUMBER]; | |
bool connected[MAX_POINT_NUMBER]; | |
int m,n; | |
int prim() | |
{ | |
int point=0; | |
int cost=0; | |
while(!GraphSet.empty())GraphSet.pop(); | |
memset(usedEdgeId,0,sizeof(usedEdgeId)); | |
memset(connected,0,sizeof(connected)); | |
connected[point]=true; | |
for(int i=0;i<n-1;i++) | |
{ | |
for(vector<edge>::iterator iter=g[point].begin();iter!=g[point].end();iter++) | |
{ | |
if(!usedEdgeId[(*iter).id]) | |
{ | |
usedEdgeId[(*iter).id]=true; | |
GraphSet.push(*iter); | |
} | |
} | |
while(!GraphSet.empty()) | |
{ | |
edge tmp=GraphSet.top(); | |
GraphSet.pop(); | |
if(!connected[tmp.dest]) | |
{ | |
connected[tmp.dest]=true; | |
//cout <<"Connected: "<<tmp.ori<<" "<<tmp.dest<<endl; | |
cost+=tmp.length; | |
point=tmp.dest; | |
break; | |
} | |
} | |
} | |
return cost; | |
} | |
int main() | |
{ | |
cin >>n>>m; | |
for(int i=0,id=0;i<m;i++) | |
{ | |
int a,b,v; | |
cin >>a>>b>>v;a--;b--; | |
edge e; | |
e.id=id++; | |
e.ori=a;e.dest=b;e.length=v; | |
g[a].push_back(e); | |
e.ori=b;e.dest=a;e.length=v; | |
g[b].push_back(e); | |
} | |
cout <<prim()<<endl; | |
return 0; | |
} |
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