simplify path structure

1 files changed, 47 insertions, 0 deletions

diff --git a/src/com.example.portfolio3/com/example/portfolio3/AdjListGraph.java b/src/com.example.portfolio3/com/example/portfolio3/AdjListGraph.java
new file mode 100644
index 0000000..a677d3e
--- /dev/null
+++ b/src/com.example.portfolio3/com/example/portfolio3/AdjListGraph.java
@@ -0,0 +1,47 @@
+package com.example.portfolio3;
+
+// origin: <https://moodle.ruc.dk/course/section.php?id=211877>
+
+import java.util.*;
+
+///  Adjecency List Graph - A map from vertices to set of outedges from the vertex
+public class AdjListGraph extends AbstractGraph {
+
+  /// foo
+  public AdjListGraph() {}
+
+  /// foo
+  private Map<Vertex,Set<Edge>> outEdge= new HashMap<>();
+
+  /// foo
+  public void insertEdge(Vertex v1,Vertex v2,int w){
+    Edge e=new Edge(v1,v2,w);
+    if(!outEdge.containsKey(e.from()))
+      outEdge.put(e.from(),new HashSet<Edge>());
+    outEdge.get(e.from()).add(e);
+  }
+
+  /// foo
+  public Collection<Edge> edges(){
+    Set<Edge> edges=new HashSet<>();
+    for(Vertex v:outEdge.keySet())edges.addAll(outEdge.get(v));
+    return edges;
+  }
+
+  /// foo
+  public Collection<Edge> outEdge(Vertex v){
+    if(!outEdge.containsKey(v))
+      return new HashSet<Edge>();
+    return outEdge.get(v);
+  }
+
+  /// foo
+  public Integer getWeight(Vertex v1,Vertex v2){
+    // linear in number of outedges from vertices
+    if(!outEdge.containsKey(v1))return null;
+    for(Edge e:outEdge.get(v1)){
+      if(e.to()==v2)return e.weight();
+    }
+    return null;
+  }
+}