import java.io.BufferedReader;import java.io.DataInputStream;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStreamReader;public class PS1Q3 { static int[][] graph; static int numNodes; static int[] tree;//it has just edges tree[i] contains j if (i,j) is in tree. This array is NOT symmetric. init to -1
 
 /*  * implements slow O(mn) algo default one  */ public static void primsSlow(){  int weight = 0;  boolean[] status = new boolean[numNodes];  for (boolean i : status)   i = false;  status[0] = true;  int minw = Integer.MAX_VALUE;  int mini =0 ;  int minj = 0;  while(!isComplete(status)){   for(int i =0;i<numNodes;i++){    if
 
 (status[i]) continue;    //find in graph an edge with (i,j) where j=true and trace minimum    for(int j =0;j<numNodes;j++){     if (!status[j]) continue;     if (minw > graph[i][j]){      minw = graph[i][j];      mini=i;//new node      minj=j;//old node     }         }   }   status[mini] = true;   tree[minj] = mini;   weight += graph[mini][minj];   minw = Integer.MAX_VALUE;  }  System.out.println("weight "
 
+weight); } public static boolean isComplete(boolean[] status){  for (boolean b : status){   if (!b) return false;  }  return true; } public static void main(String[] args) {  // TODO Auto-generated method stub  try {   FileInputStream f = new FileInputStream("edges.txt");   DataInputStream d = new DataInputStream(f);   BufferedReader b = new BufferedReader(new InputStreamReader(f));   numNodes = Integer.parseInt(b.readLine().split(" ")[0]);   graph = new int[numNodes][numNodes];   for (int i =0;i<numNodes;i++)    for(int j=0; j < numNodes; j++)     graph[i][j] =Integer.MAX_VALUE;   String str;   while((str=b.readLine())!=null){    int i = Integer.parseInt(str.split(" ")[0])-1;    int j = Integer.parseInt(str.split(" ")[1])-1;    graph[i][j] = Integer.parseInt(str.split(" ")[2]);    graph[j][i] = Integer.parseInt(str.split(" ")[2]);   }   tree = new int[numNodes];   for (int i : tree)    i=-1;   primsSlow();  } catch (NumberFormatException | IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } }}