Merge pull request #47 from Data-Structure-Study/yoonexample

DFS BFS 구현

Author: ksundong

yoonexample/src/main/java/graph/Graph.java

@@ -17,6 +17,24 @@ public interface Graph {
 
   /**
    * 그래프의 간선정보를 반환합니다.
+   *
+   * @return 그래프의 간선정보
    */
   String showGraphEdgeInfo();
+
+  /**
+   * startV를 기점으로 DFS를 수행한 결과를 반환합니다.
+   *
+   * @param startV DFS를 시작하는 정점
+   * @return startV를 기점으로 하는 DFS 결과
+   */
+  String depthFirstSearch(Enum<?> startV);
+
+  /**
+   * startV를 기점으로 BFS를 수행한 결과를 반환합니다.
+   *
+   * @param startV BFS를 시작하는 정점
+   * @return startV를 기점으로 하는 BFS 결과
+   */
+  String breadthFirstSearch(Enum<?> startV);
 }

yoonexample/src/main/java/graph/ListGraph.java

@@ -1,7 +1,12 @@
 package graph;
 
+import java.util.StringJoiner;
 import list.DummyDoublyLinkedList;
 import list.List;
+import queue.LinkedListQueue;
+import queue.Queue;
+import stack.ListStack;
+import stack.Stack;
 
 public class ListGraph implements Graph {
 
@@ -44,4 +49,64 @@ public String showGraphEdgeInfo() {
 
     return sb.toString();
   }
+
+  @Override
+  public String depthFirstSearch(Enum<?> startV) {
+    boolean[] visited = new boolean[vertices.length];
+    StringJoiner sj = new StringJoiner(" ");
+    Stack<Enum<?>> vertexStack = new ListStack<>();
+    vertexStack.push(startV);
+
+    while (!vertexStack.isEmpty()) {
+      Enum<?> visitV = vertexStack.pop();
+
+      if (visitVertex(visited, visitV)) {
+        sj.add(visitV.toString());
+      }
+      List<Enum<?>> vertexList = vertices[visitV.ordinal()];
+      for (int i = 0; i < vertexList.size(); i++) {
+        Enum<?> vertex = vertexList.get(i);
+        if (!visited[vertex.ordinal()]) {
+          vertexStack.push(vertex);
+        }
+      }
+    }
+
+    return sj.toString();
+  }
+
+  @Override
+  public String breadthFirstSearch(Enum<?> startV) {
+    boolean[] visited = new boolean[vertices.length];
+    StringJoiner sj = new StringJoiner(" ");
+    Queue<Enum<?>> vertexQueue = new LinkedListQueue<>();
+    vertexQueue.enqueue(startV);
+
+    while (!vertexQueue.isEmpty()) {
+      Enum<?> visitV = vertexQueue.dequeue();
+
+      if (visitVertex(visited, visitV)) {
+        sj.add(visitV.toString());
+      }
+
+      List<Enum<?>> vertexList = vertices[visitV.ordinal()];
+      for (int i = 0; i < vertexList.size(); i++) {
+        Enum<?> vertex = vertexList.get(i);
+        if (!visited[vertex.ordinal()]) {
+          vertexQueue.enqueue(vertex);
+        }
+      }
+
+    }
+
+    return sj.toString();
+  }
+
+  private boolean visitVertex(boolean[] visited, Enum<?> vertex) {
+    if (visited[vertex.ordinal()]) {
+      return false;
+    }
+    visited[vertex.ordinal()] = true;
+    return true;
+  }
 }

yoonexample/src/test/java/graph/GraphTest.java

@@ -40,6 +40,38 @@ void setUp() {
     assertThat(graph.showGraphEdgeInfo()).isEqualTo("A: B D E\nB: A C\nC: B D\nD: A C E\nE: D A\n");
   }
 
+  @Test
+  void dfsTest() {
+    setVertices();
+
+    assertThat(graph.depthFirstSearch(Point.A)).isEqualTo("A E D C B");
+    assertThat(graph.depthFirstSearch(Point.B)).isEqualTo("B E D C A");
+    assertThat(graph.depthFirstSearch(Point.C)).isEqualTo("C D E B A");
+    assertThat(graph.depthFirstSearch(Point.D)).isEqualTo("D E B A C");
+    assertThat(graph.depthFirstSearch(Point.E)).isEqualTo("E D C A B");
+  }
+
+  @Test
+  void bfsTest() {
+    setVertices();
+
+    assertThat(graph.breadthFirstSearch(Point.A)).isEqualTo("A B C E D");
+    assertThat(graph.breadthFirstSearch(Point.B)).isEqualTo("B A D E C");
+    assertThat(graph.breadthFirstSearch(Point.C)).isEqualTo("C A D B E");
+    assertThat(graph.breadthFirstSearch(Point.D)).isEqualTo("D B C E A");
+    assertThat(graph.breadthFirstSearch(Point.E)).isEqualTo("E A B D C");
+  }
+
+  private void setVertices() {
+    graph.addEdge(Point.A, Point.B);
+    graph.addEdge(Point.A, Point.C);
+    graph.addEdge(Point.A, Point.E);
+    graph.addEdge(Point.B, Point.D);
+    graph.addEdge(Point.B, Point.E);
+    graph.addEdge(Point.C, Point.D);
+    graph.addEdge(Point.D, Point.E);
+  }
+
   private enum Point {
     A, B, C, D, E, F, G, H, I, J
   }