// Kruskal's algorithm in Java
import java.util.*;
class Graph {
class Edge implements Comparable {
int src, dest, weight;
public int compareTo(Edge compareEdge) {
return this.weight - compareEdge.weight;
}
};
// Union
class subset {
int parent, rank;
};
int vertices, edges;
Edge edge[];
// Graph creation
Graph(int v, int e) {
vertices = v;
edges = e;
edge = new Edge[edges];
for (int i = 0; i < e; ++i)
edge[i] = new Edge();
}
int find(subset subsets[], int i) {
if (subsets[i].parent != i)
subsets[i].parent = find(subsets, subsets[i].parent);
return subsets[i].parent;
}
void Union(subset subsets[], int x, int y) {
int xroot = find(subsets, x);
int yroot = find(subsets, y);
if (subsets[xroot].rank < subsets[yroot].rank)
subsets[xroot].parent = yroot;
else if (subsets[xroot].rank > subsets[yroot].rank)
subsets[yroot].parent = xroot;
else {
subsets[yroot].parent = xroot;
subsets[xroot].rank++;
}
}
// Applying Krushkal Algorithm
void KruskalAlgo() {
Edge result[] = new Edge[vertices];
int e = 0;
int i = 0;
for (i = 0; i < vertices; ++i)
result[i] = new Edge();
// Sorting the edges
Arrays.sort(edge);
subset subsets[] = new subset[vertices];
for (i = 0; i < vertices; ++i)
subsets[i] = new subset();
for (int v = 0; v < vertices; ++v) {
subsets[v].parent = v;
subsets[v].rank = 0;
}
i = 0;
while (e < vertices - 1) {
Edge next_edge = new Edge();
next_edge = edge[i++];
int x = find(subsets, next_edge.src);
int y = find(subsets, next_edge.dest);
if (x != y) {
result[e++] = next_edge;
Union(subsets, x, y);
}
}
for (i = 0; i < e; ++i)
System.out.println(result[i].src + " - " + result[i].dest + ": " + result[i].weight);
}
public static void main(String[] args) {
int vertices = 6; // Number of vertices
int edges = 8; // Number of edges
Graph G = new Graph(vertices, edges);
G.edge[0].src = 0;
G.edge[0].dest = 1;
G.edge[0].weight = 4;
G.edge[1].src = 0;
G.edge[1].dest = 2;
G.edge[1].weight = 4;
G.edge[2].src = 1;
G.edge[2].dest = 2;
G.edge[2].weight = 2;
G.edge[3].src = 2;
G.edge[3].dest = 3;
G.edge[3].weight = 3;
G.edge[4].src = 2;
G.edge[4].dest = 5;
G.edge[4].weight = 2;
G.edge[5].src = 2;
G.edge[5].dest = 4;
G.edge[5].weight = 4;
G.edge[6].src = 3;
G.edge[6].dest = 4;
G.edge[6].weight = 3;
G.edge[7].src = 5;
G.edge[7].dest = 4;
G.edge[7].weight = 3;
G.KruskalAlgo();
}
}