connectedComponent.java

import java.util.*;

public class connectedComponent {
    static class Edge {
        int src;
        int dest;
        int weight;

        Edge(int src, int dest, int weight) {
            this.src = src;
            this.dest = dest;
            this.weight = weight;
        }
    }

    public static void createGraph(ArrayList<Edge>[] graph) {
        for (int i = 0; i < graph.length; i++) {
            graph[i] = new ArrayList<>();
        }
        // 0 Edge
        graph[0].add(new Edge(0, 1, 1));
        graph[0].add(new Edge(0, 2, 1));
        // 1 Edge
        graph[1].add(new Edge(1, 0, 1));
        graph[1].add(new Edge(1, 3, 1));
        // 2 Edge
        graph[2].add(new Edge(2, 0, 1));
        graph[2].add(new Edge(2, 4, 1));
        // 3 Edge
        graph[3].add(new Edge(3, 1, 1));
        graph[3].add(new Edge(3, 4, 1));
        graph[3].add(new Edge(3, 5, 1));
        // 4 Edge
        graph[4].add(new Edge(4, 5, 1));
        graph[4].add(new Edge(4, 3, 1));
        graph[4].add(new Edge(4, 2, 1));
        // 5 Edge
        graph[5].add(new Edge(5, 6, 1));
        graph[5].add(new Edge(5, 3, 1));
        graph[5].add(new Edge(5, 4, 1));
        // 6 Edge
        graph[6].add(new Edge(6, 5, 1));

    }

    public static void dfs1(ArrayList<Edge>[] graph, int curr, boolean vis[]) {
        // visit
        System.out.print(curr + " ");
        vis[curr] = true;
        for (int i = 0; i < graph[curr].size(); i++) {
            Edge e = graph[curr].get(i);
            if (!vis[e.dest]) {
                dfs1(graph, e.dest, vis);
            }
        }
    }

    public static void dfs(ArrayList<Edge> graph[]) {
        boolean vis[] = new boolean[graph.length];
        for (int i = 0; i < graph.length; i++) {
            if (!vis[i]) {
                dfsUtil(graph, i, vis);
            }

        }
    }

    private static void dfsUtil(ArrayList<connectedComponent.Edge>[] graph, int curr, boolean[] vis) {

        System.out.print(curr + " ");

        vis[curr] = true;
        for (int i = 0; i < graph[curr].size(); i++) {
            Edge e = graph[curr].get(i);
            if (!vis[e.dest]) {
                dfsUtil(graph, e.dest, vis);
            }
        }
    }

    public static void bfs1(ArrayList<Edge>[] graph) {
        Queue<Integer> q = new LinkedList<>();
        boolean vis[] = new boolean[graph.length];
        q.add(0);
        while (!q.isEmpty()) {
            int curr = q.remove();
            if (!vis[curr]) {
                System.out.print(curr + " ");
                vis[curr] = true;
                for (int i = 0; i < graph[curr].size(); i++) {
                    Edge e = graph[curr].get(i);
                    q.add(e.dest);
                }
            }
        }

    }

    public static void bfs(ArrayList<Edge> graph[]) {
        boolean vis[] = new boolean[graph.length];
        for (int i = 0; i < graph.length; i++) {
            if (!vis[i]) {
                bfsUtil(graph, vis);
            }
        }
    }

    private static void bfsUtil(ArrayList<connectedComponent.Edge>[] graph, boolean[] vis) {
        Queue<Integer> q = new LinkedList<>();
        q.add(0); // source = 0

        while (!q.isEmpty()) {
            int curr = q.remove();

            if (!vis[curr]) {
                System.out.print(curr + " ");
                vis[curr] = true;
                for (int i = 0; i < graph[curr].size(); i++) {
                    Edge e = graph[curr].get(i);
                    q.add(e.dest);
                }
            }

        }
    }

    public static void main(String[] args) {
        int v = 7;
        ArrayList<Edge>[] graph = new ArrayList[v];
        createGraph(graph);

        System.out.println("\nBreadth first Search (BFS)");
        bfs(graph);

        System.out.println("\n\nDepth first Search (DFS)");
        dfs(graph);
    }
}

/*
 * Output:
 * Breadth first Search (BFS)
 * 0 1 2 3 4 5 6
 * 
 * Depth first Search (DFS)
 * 0 1 3 4 5 6 2
 * 
 */