[Function add]

1.Add DFS for graph search.

Author: Seanforfun

Diff for: Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/DeepFirstSearch.java

@@ -0,0 +1,37 @@
+package ca.mcmaster.chapter.four.graph;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+
+public class DeepFirstSearch extends AbstractSearch {
+	private boolean[] marked;
+	private int count;
+	public DeepFirstSearch(Graph g, int s) {
+		super(g, s);
+		marked = new boolean[g.V()];
+		dfs(g, s);
+	}	
+	private void dfs(Graph g, int v){
+		marked[v] = true;	//It means current vertex has been accessed.
+		count++;	//update the number of vertex connected to s.
+		for(int w : g.adj(v))
+			if(!marked[w]) dfs(g, w);	//Check all point connected to v, if not accessed, access recursively.
+	}
+	@Override
+	public boolean mark(int v) {
+		return marked[v];
+	}
+	@Override
+	public int count() {
+		return this.count;
+	}
+	
+	public static void main(String[] args) throws FileNotFoundException {
+		Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
+		Search search = new DeepFirstSearch(g, 12);
+		System.out.println(search.mark(9));
+		System.out.println(search.count());
+		g.display();
+	}
+}

Diff for: Algorithm(4th_Edition)/src/ca/mcmaster/chapter/four/graph/Graph.java

@@ -86,7 +86,7 @@ default void display(){
 		for(int v = 0; v < vertexNum; v++){
 			StringBuilder sb = new StringBuilder(v + " -> ");
 			for(int w : adj(v))
-				sb.append(w + "");
+				sb.append(w + " ");
 			System.out.println(sb.toString());
 		}
 	}

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

@@ -28,6 +28,7 @@ public int count() {
 		return uf.size[super.s];
 	}
 	private final class UF{
+		@SuppressWarnings("unused")
 		private final int N;
 		private final int[] a;
 		private final int[] size;
@@ -61,7 +62,8 @@ public boolean connected(int p, int q){
 
 	public static void main(String[] args) throws FileNotFoundException {
 		Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
-		Search search = new UFSearch(g, 9);
-		System.out.println(search.mark(4));
+		Search search = new UFSearch(g, 3);
+		System.out.println(search.mark(7));
+		g.display();
 	}
 }

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

@@ -8,6 +8,7 @@
 
 public class UndirectedGraph implements Graph {
 	private final int V; //vertex
+	@SuppressWarnings("unused")
 	private int E;	//edge
 	private Bag<Integer>[] adj;	//adjacency table.
 	@SuppressWarnings("unchecked")

Diff for: DataStructrue/Graph/UndirectedGraph.md

@@ -224,4 +224,65 @@ public class UFSearch extends AbstractSearch {
 	}
 
 }
+```
+
+#### UFSearch测试
+```Java
+		Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
+		Search search = new UFSearch(g, 3);
+		System.out.println(search.mark(7));
+		g.display();
+```
+* 结果
+>false
+>0 -> 6 2 1 5
+>1 -> 0
+>2 -> 0
+>3 -> 5 4
+>4 -> 5 6 3
+>5 -> 3 4 0
+>6 -> 0 4
+>7 -> 8
+>8 -> 7
+>9 -> 11 10 12
+>10 -> 9
+>11 -> 9 12
+>12 -> 11 9
+
+#### 深度优先查找DFSearch
+```Java
+public class DeepFirstSearch extends AbstractSearch {
+	private boolean[] marked;	//A array used to mark if current node is connected to s
+	private int count;	//number of vertex connected to s
+	public DeepFirstSearch(Graph g, int s) {
+		super(g, s);
+		marked = new boolean[g.V()];
+		dfs(g, s);
+	}
+	private void dfs(Graph g, int v){
+		marked[v] = true;	//It means current vertex has been accessed.
+		count++;	//update the number of vertex connected to s.
+		for(int w : g.adj(v))
+			if(!marked[w]) dfs(g, w);	//Check all point connected to v, if not accessed, access recursively.
+	}
+	@Override
+	public boolean mark(int v) {
+		return marked[v];
+	}
+	@Override
+	public int count() {
+		return this.count;
+	}
+}
+```
+
+#### 测试
+```Java
+	public static void main(String[] args) throws FileNotFoundException {
+		Graph g = new UndirectedGraph(new FileInputStream(new File("src/ca/mcmaster/chapter/four/graph/tinyG.txt")));
+		Search search = new DeepFirstSearch(g, 12);
+		System.out.println(search.mark(9));
+		System.out.println(search.count());
+		g.display();
+	}
 ```