Kruskal Algorithm added

src/main/java/com/thealgorithms/greedyalgorithms/KruskalAlgorithm.java

@@ -0,0 +1,102 @@
+package com.thealgorithms.greedyalgorithms;
+
+import java.util.*;
+
+class Edge implements Comparable<Edge> {
+    int src, dest, weight;
+
+    Edge(int src, int dest, int weight) {
+        this.src = src;
+        this.dest = dest;
+        this.weight = weight;
+    }
+
+    @Override
+    public int compareTo(Edge other) {
+        return this.weight - other.weight;
+    }
+}
+
+class DisjointSet {
+    int[] parent, rank;
+
+    DisjointSet(int n) {
+        parent = new int[n];
+        rank = new int[n];
+        for (int i = 0; i < n; i++) {
+            parent[i] = i;
+            rank[i] = 0;
+        }
+    }
+
+    int find(int x) {
+        if (parent[x] != x) {
+            parent[x] = find(parent[x]);    
+        }
+        return parent[x];
+    }
+
+    void union(int x, int y) {
+        int rootX = find(x);
+        int rootY = find(y);
+
+        if (rootX != rootY) {
+            if (rank[rootX] < rank[rootY]) {
+                parent[rootX] = rootY;
+            } else if (rank[rootX] > rank[rootY]) {
+                parent[rootY] = rootX;
+            } else {
+                parent[rootY] = rootX;
+                rank[rootX]++;
+            }
+        }
+    }
+}
+
+public class KruskalAlgorithm {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        System.out.print("Enter number of vertices: ");
+        int vertices = sc.nextInt();
+
+        System.out.print("Enter number of edges: ");
+        int edgesCount = sc.nextInt();
+
+        List<Edge> edges = new ArrayList<>();
+
+        System.out.println("Enter edges (src dest weight):");
+        for (int i = 0; i < edgesCount; i++) {
+            int src = sc.nextInt();
+            int dest = sc.nextInt();
+            int weight = sc.nextInt();
+            edges.add(new Edge(src, dest, weight));
+        }
+
+        Collections.sort(edges);
+
+        DisjointSet ds = new DisjointSet(vertices);
+        List<Edge> mst = new ArrayList<>();
+
+        for (Edge edge : edges) {
+            int root1 = ds.find(edge.src);
+            int root2 = ds.find(edge.dest);
+
+            if (root1 != root2) {
+                mst.add(edge);
+                ds.union(root1, root2);
+            }
+        }
+
+        System.out.println("\nMinimum Spanning Tree:");
+        int totalWeight = 0;
+        for (Edge e : mst) {
+            System.out.println(e.src + " -- " + e.dest + " == " + e.weight);
+            totalWeight += e.weight;
+        }
+
+        System.out.println("Total Weight = " + totalWeight);
+        sc.close();
+    }
+}