Algorithms/prims,java at master · ravikiradoo/Algorithms · GitHub

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import java.io.*;
import java.util.*;

class Edge
{
    int dst;
    int weight;

}

class Graph{

    int V;
    int E;
    ArrayList<Edge> Edges[];
    int parent[];
    Edge result[];
    boolean mstSet[];
    int key[];
	Graph(int v)
	{
	    V=v;
	    Edges=new ArrayList[V];
	    parent=new int[V];
	    mstSet=new boolean[V];
	    result=new Edge[V];
	    key=new int[V];
	 	for(int i=0;i<V;i++)
    	{
    	Edges[i]=new ArrayList<Edge>();
    	parent[i]=i;
    	mstSet[i]=false;
    	key[i]=Integer.MAX_VALUE;
    	}
    	key[0]=0;
    	parent[0]=-1;

	}
	void AddEdges(int a,int b,int c)
	{
	   Edge edge=new Edge();
	   edge.dst=b;
	   edge.weight=c;
	   Edges[a].add(edge);
	}

void PrimMst()
{


    for(int i=0;i<V-1;i++)
    {
            int u=minkey();

        mstSet[u]=true;
        for(int j=0;j<Edges[u].size();j++)
        {
            if(mstSet[Edges[u].get(j).dst]==false && Edges[u].get(j).weight<key[Edges[u].get(j).dst])
            {
                parent[Edges[u].get(j).dst]=u;
                key[Edges[u].get(j).dst]=Edges[u].get(j).weight;
            }
        }

    }

}
int minkey()
{
    int min=Integer.MAX_VALUE;
    int index=-1;
    for(int i=0;i<V;i++)
    {
        if(mstSet[i]==false && key[i]<min)
        {
            min=key[i];
            index=i;
        }

    }
    return index;
}


}
class Main
{
    public static void main(String args[])
    {
        Scanner scan = new Scanner(System.in);


        int n= scan.nextInt();
        Graph graph=new Graph(n);
        int e=scan.nextInt();

      for(int i=0;i<e;i++)
      {
          graph.AddEdges(scan.nextInt(),scan.nextInt(),scan.nextInt());
      }

       graph.PrimMst();
          for(int i=1;i<n;i++)
          {
              System.out.println(graph.parent[i]+"->"+i+" "+graph.key[i]);
          }

          }


   }