JavaDataStructures/GraphAPI/Graph.java at master · guvenbe/JavaDataStructures · GitHub

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package GraphAPI;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileReader;

import java.io.IOException;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Stack;

public class Graph {

int v, e, connex;

List<Integer>[] adj;

boolean[] marked, color;

int[] parent, id;

boolean bipart = true, isCycle = false;

Stack<Integer> reverseOrder;

public Graph(int n) {

this.v = n;

adj = new List[n];

for (int i = 0; i < n; i++) {

adj[i] = new LinkedList<>();

}

/* constructor from a file */

public Graph(File file) {

BufferedReader reader;

try {

reader = new BufferedReader(new FileReader(file));

String line;

v = Integer.parseInt(reader.readLine()); //number of elements (1st line)

e = Integer.parseInt(reader.readLine()); //number of edges (2nd line)

adj = new List[v];

for (int i = 0; i < v; i++) {

adj[i] = new LinkedList<>();

}

while ((line = reader.readLine()) != null) {

String[] parts = line.split("\\s");

int from = Integer.parseInt(parts[0]);

int to = Integer.parseInt(parts[1]);

adj[from].add(to);

}

reader.close();

} catch (IOException ex) {

}

/* add edge for directed graph */

public void addEdge(int v, int w)

{

adj[v].add(w);

}

public void init() {

parent = new int[v];

id = new int[v];

marked = new boolean[v];

color = new boolean[v];

connex = 0;

reverseOrder = new Stack<>();

}

/* Depth-First Search */

public void dfs(int s) {

id[s] = connex;

marked[s] = true;

adj[s].stream().forEach((x) -> {

if (!marked[x]) {

color[x] = !color[s];

parent[x] = s;

dfs(x);

} else if (color[x] = color[s]) {

bipart = false;

} else {

//not working need dfs(s, origin)

isCycle = true;

}

});

if(!adj[s].isEmpty())

reverseOrder.push(s);

}

/* start a Depth-First Search */

public void exProfondeur(int s) {

init();

dfs(s);

}

/* ckeck if a path exist between a and b */

public boolean pathExist(int a, int b) {

exProfondeur(a);

return marked[b];

}

/* get a path between a and b */

public Stack<Integer> getPath(int a, int b)

{

if (!pathExist(a, b)) return null;

Stack<Integer> path = new Stack<>();

while (a != b) {

path.push(b);

b = parent[b];

}

path.push(a);

return path;

}

/* check if all element of the graph are connected */

public boolean isConnexe() {

exProfondeur(adj[0].get(0));

for (boolean isMarked : marked) {

if (!isMarked) {

return false;

}

return true;

}

/* count numbre of connexe */

public void countConnexe() {

for (int i = 0; i < v; i++) {

if (!marked[i]) {

dfs(i);

connex++;

}

/* check if two components are connected */

public boolean areConnected(int C1, int C2) {

return id[C1] == id[C2];

}

/* get connexe by id */

public List<Integer> getConnexe(int v) {

List<Integer> list = new LinkedList<>();

for (int i = 0; i < v; i++) {

if (id[i] == v) {

list.add(i);

}

return list;

}

/* get all connected componenets */

public Map<Integer, List<Integer>> getAllConnexe(int v) {

Map<Integer, List<Integer>> map = new HashMap<>();

for (int i = 0; i < id.length; i++) {

List<Integer> l = map.get(id[i]);

if (l == null) {

l = new LinkedList<>();

}

l.add(i);

map.put(id[i], l);

}

return map;

}

/* check if this graph has a cycle */

public boolean hasCycle() {

init();

for (int i : id) {

dfs(i);

}

return isCycle;

}

/* still figuring it out */

boolean bipart() {

init();

dfs(0);

return bipart;

}

/* breadth first search */

public void bfs(int s) {

LinkedList<Integer> q = new LinkedList<>();

q.addLast(s);

marked[s] = true;

while (!q.isEmpty()) {

s = q.getFirst();

for (int w : adj[s]) {

if (!marked[w]) {

q.addLast(w);

parent[w] = s;

marked[w] = true;

}

public Stack<Integer> topologicalOrder(){

init();

for (int i = 0; i < v; i++) {

if(!marked[i]) dfs(i);

}

return reverseOrder;

}

/* print the graph (obviously) */

public void print(){

for (int i = 0; i < v; i++) {

System.out.print(i + " -> ");

adj[i].stream().forEach(x->{System.out.print( x + " ");});

System.out.println("");

}

/* testing */

public static void main(String[] args) {

File file = new File("src/GraphAPI/data.txt");

Graph g = new Graph(file);

System.out.println("------- Graph -------");

g.print();

System.out.println("------- hasCycle -------");

if(g.hasCycle())

System.out.println("yes");

else System.out.println("no");

System.out.println("------- pathExist(0, 4) -------");

if(g.pathExist(0, 4))

System.out.println("yes");

else System.out.println("no");

System.out.println("------- pathExist(3, 0) -------");

if(g.pathExist(3, 0))

System.out.println("yes");

else System.out.println("no");

System.out.println("------- path(3, 0) -------");

Stack<Integer> path1 = g.getPath(3,0);

while (!path1.isEmpty()) {

System.out.print(path1.pop() + " -> ");

}

System.out.println("");

System.out.println("------- isConnexe -------");

if(g.isConnexe())

System.out.println("yes");

else System.out.println("no");

System.out.println("------- countConnex -------");

g.countConnexe();

System.out.println(g.connex);

System.out.println("------- topologicalOrder -------");

Stack<Integer> path = g.topologicalOrder();

while (!path.isEmpty()) {

System.out.print(path.pop() + " -> ");

}

System.out.println("");

}

JavaDataStructures/GraphAPI/Graph.java at master · guvenbe/JavaDataStructures · GitHub

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