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Kruskals.java
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Kruskals.java
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import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.PriorityQueue;
import java.util.Scanner;
class Edge implements Comparable<Edge>{
int value;
String u;
String v;
public Edge() {//initializing variables
value = 0;
u = "";
v = "";
}
public Edge( int val, String left, String right ) {
value = val;
u = left;
v = right;
}
public int compareTo(Edge e) {
return this.value - e.value;
}
@Override
public boolean equals(Object o) {
if(!(o instanceof Edge)) {
return false;
}
Edge e = (Edge) o;
if(this.value == e.value && this.u.equals(e.u) && this.v.equals(e.v)) {
return true;
}else if(this.value == e.value && this.v.equals(e.u) && this.u.equals(e.v)) {
return true;
}
return false;
}
}
public class Kruskals {
public static void main(String[] args) {
// TODO Auto-generated method stub
PriorityQueue<Edge> pq = new PriorityQueue<Edge>();
ArrayList<String> city = new ArrayList<>();
HashMap<String, Integer> map = new HashMap<>();
Scanner sc = new Scanner(System.in);
Edge ed;
//File file = new File("C:/Users/Rishav-PC/eclipse-workspace/kruskals/assn9_data.csv"); //for absolute path
File file = new File("assn9_data.csv"); //for direct path
//System.err.println(file.getAbsolutePath());
try {
Scanner fl = new Scanner(file);
while(fl.hasNextLine()) {
String s = fl.nextLine();
String [] ar = s.split(",");
city.add(ar[0]);
for(int i = 1; i < ar.length-1; i+=2) {
ed = new Edge(Integer.parseInt(ar[i+1]) ,ar[0], ar[i]);
if(!pq.contains(ed)) {
pq.add(ed);
}
}
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
for(int i = 0; i < city.size(); i++) {
map.put(city.get(i), i);
}
DisjSets ds = new DisjSets(city.size());
int edgesAccepted = 0;
int totalDistance = 0;
while(edgesAccepted < city.size() - 1) {
ed = pq.poll();
if(ds.find(map.get(ed.u)) != ds.find(map.get(ed.v))) {
// accept the edge
edgesAccepted++;
ds.union(ds.find(map.get(ed.u)), ds.find(map.get(ed.v)));
System.out.println(ed.u + " "+ ed.v + " " + ed.value);
totalDistance += ed.value;
}
}
System.out.println();
System.out.println("Total Distance is: " + totalDistance);
}
}