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[Function add]
1.Add undirected graph. 2.Add a union find implementation of Search:UFSearch.
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‎Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/AbstractSearch.java

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package ca.mcmaster.chapter.four.graph;
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public abstract class AbstractSearch implements Search {
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protected final Graph g;
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protected final int s;
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public AbstractSearch(Graph g, int s) {
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this.g = g;
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this.s = s;
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}
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}

‎Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/Search.java

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package ca.mcmaster.chapter.four.graph;
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public interface Search {
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/**
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* @Description: If s and v are connected.
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* @param v
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* @return
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*/
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public boolean mark(int v);
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/**
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* @Description: Number of vertex connected to source.
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* @return
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*/
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public int count();
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}

‎Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/UFSearch.java

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package ca.mcmaster.chapter.four.graph;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileNotFoundException;
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public class UFSearch extends AbstractSearch {
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private final UF uf;
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public UFSearch(Graph g, int s) {
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super(g, s);
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this.uf = new UF(g.V());
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//Insert connections into the UF.
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for(int v = 0; v < g.V(); v++){
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for(int w : g.adj(v)){
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if(uf.connected(v, w)) continue;
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else uf.union(v, w);
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}
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}
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}
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@Override
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public boolean mark(int v) {
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return uf.connected(super.s, v);
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}
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@Override
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public int count() {
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return uf.size[super.s];
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}
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private final class UF{
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private final int N;
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private final int[] a;
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private final int[] size;
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public UF(int N){
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this.N = N;
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a = new int[N];
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for(int i = 0; i < N; i++) a[i] = i;
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size = new int[N];
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for(int i = 0; i < N; i++) size[i] = 1;
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}
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public int find(int v){
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if(a[v] == v) return v;
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else return find(a[v]);
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}
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public void union(int p, int q){
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int qRoot = find(q);
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int pRoot = find(p);
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if(pRoot == qRoot) return;
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if(size[qRoot] < size[pRoot]){
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a[qRoot] = pRoot;
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size[pRoot] += size[qRoot];
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}else{ //size[qRoot] >= size[pRoot]
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a[pRoot] = qRoot;
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size[qRoot] += size[pRoot];
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}
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}
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public boolean connected(int p, int q){
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return find(q) == find(p);
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}
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}
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public static void main(String[] args) throws FileNotFoundException {
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Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
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Search search = new UFSearch(g, 9);
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System.out.println(search.mark(4));
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}
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}

‎Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/UndirectedGraph.java

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package ca.mcmaster.chapter.four.graph;
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import java.io.FileInputStream;
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import java.util.Scanner;
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import ca.mcmaster.chapter.one.bag.Bag;
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import ca.mcmaster.chapter.one.bag.ListBag;
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public class UndirectedGraph implements Graph {
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private final int V; //vertex
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private int E; //edge
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private Bag<Integer>[] adj; //adjacency table.
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@SuppressWarnings("unchecked")
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public UndirectedGraph(int V) {
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this.V = V;
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adj = new ListBag[V];
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for(int v = 0; v < V; v++)
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adj[v] = new ListBag<>();
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}
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@SuppressWarnings("unchecked")
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public UndirectedGraph(FileInputStream in){
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Scanner scanner = new Scanner(in);
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this.V = scanner.nextInt();
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adj = new ListBag[V];
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for(int v = 0; v < V; v++)
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adj[v] = new ListBag<>();
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int E = scanner.nextInt();
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for(int e = 0; e < E; e++){
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int v = scanner.nextInt();
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int w = scanner.nextInt();
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addEdge(v, w);
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}
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scanner.close();
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}
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@Override
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public int V() { return V; }
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@Override
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public int E() { return 0; }
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@Override
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public void addEdge(int v, int w) {
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adj[v].add(w);
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adj[w].add(v);
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this.E++;
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}
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@Override
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public Iterable<Integer> adj(int v) {
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return adj[v];
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}
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}

‎Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/tinyG.txt

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13
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13
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0 5
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4 3
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0 1
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9 12
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6 4
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5 4
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0 2
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11 12
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9 10
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0 6
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7 8
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9 11
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5 3

‎DataStructrue/Graph/AbstractSearch.java

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package ca.mcmaster.chapter.four.graph;
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public abstract class AbstractSearch implements Search {
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protected final Graph g;
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protected final int s;
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public AbstractSearch(Graph g, int s) {
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this.g = g;
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this.s = s;
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}
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}

‎DataStructrue/Graph/Graph.java

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package ca.mcmaster.chapter.four.graph;
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import java.awt.DisplayMode;
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public interface Graph {
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/**
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* @Description: Get the vertex number.
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* @return
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*/
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public int V();
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/**
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* @Description: Get the edge number.
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* @return
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*/
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public int E();
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/**
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* @Description: Create an edge between w and v.
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* @param v
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* @param w
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*/
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public void addEdge(int v, int w);
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/**
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* @Description: Get all vertex adjacent to v.
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* @param v
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* @return
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*/
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public Iterable<Integer> adj(int v);
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/**
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* @Description: Return degree of given vertex.
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* @param G
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* @param V
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* @return
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*/
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static Integer degree(Graph G, int V){
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Integer degree = new Integer(0);
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for(int w : G.adj(V)) degree++;
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return degree;
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}
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/**
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* @Description: Find the largest degree in the graph
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* @param G
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* @param V
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* @return
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*/
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static int maxDegree(Graph G, int V){
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int max = 0;
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for(int w : G.adj(V) )
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if(w > max)
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max = w;
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return max;
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}
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/**
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* @Description: Calculate the average degree for all vertex.
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* @param G
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* @return
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*/
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static double avgDegree(Graph G){
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return 2 * G.E() / G.V();
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}
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/**
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* @Description: Get the number of selt loop.
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* @param G
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* @param V
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* @return
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*/
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static int numOfSelfLoop(Graph G, int V){
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int num = 0;
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int vNum = G.V();
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for(int v = 0; v < vNum; v++ )
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for(int w : G.adj(v))
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if(w == v)
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num ++;
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return num/2; //w,v and v,w will both be counted.
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}
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/**
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* @Description: Print a graph.
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*/
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default void display(){
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int vertexNum = this.V();
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for(int v = 0; v < vertexNum; v++){
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StringBuilder sb = new StringBuilder(v + " -> ");
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for(int w : adj(v))
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sb.append(w + "");
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System.out.println(sb.toString());
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}
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}
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}

‎DataStructrue/Graph/Search.java

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package ca.mcmaster.chapter.four.graph;
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public interface Search {
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/**
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* @Description: If s and v are connected.
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* @param v
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* @return
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*/
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public boolean mark(int v);
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/**
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* @Description: Number of vertex connected to source.
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* @return
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*/
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public int count();
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}

‎DataStructrue/Graph/UFSearch.java

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package ca.mcmaster.chapter.four.graph;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileNotFoundException;
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public class UFSearch extends AbstractSearch {
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private final UF uf;
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public UFSearch(Graph g, int s) {
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super(g, s);
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this.uf = new UF(g.V());
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//Insert connections into the UF.
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for(int v = 0; v < g.V(); v++){
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for(int w : g.adj(v)){
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if(uf.connected(v, w)) continue;
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else uf.union(v, w);
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}
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}
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}
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@Override
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public boolean mark(int v) {
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return uf.connected(super.s, v);
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}
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@Override
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public int count() {
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return uf.size[super.s];
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}
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private final class UF{
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private final int N;
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private final int[] a;
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private final int[] size;
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public UF(int N){
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this.N = N;
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a = new int[N];
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for(int i = 0; i < N; i++) a[i] = i;
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size = new int[N];
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for(int i = 0; i < N; i++) size[i] = 1;
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}
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public int find(int v){
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if(a[v] == v) return v;
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else return find(a[v]);
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}
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public void union(int p, int q){
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int qRoot = find(q);
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int pRoot = find(p);
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if(pRoot == qRoot) return;
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if(size[qRoot] < size[pRoot]){
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a[qRoot] = pRoot;
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size[pRoot] += size[qRoot];
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}else{ //size[qRoot] >= size[pRoot]
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a[pRoot] = qRoot;
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size[qRoot] += size[pRoot];
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}
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}
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public boolean connected(int p, int q){
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return find(q) == find(p);
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}
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}
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public static void main(String[] args) throws FileNotFoundException {
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Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
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Search search = new UFSearch(g, 9);
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System.out.println(search.mark(4));
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}
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}

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