Bug found in Dijkstra class file; I wasn't updating the unvisited queue properly

Author: Justin Wetherell

src/com/jwetherell/algorithms/data_structures/Graph.java

@@ -1,6 +1,7 @@
 package com.jwetherell.algorithms.data_structures;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -57,11 +58,11 @@ public Graph(TYPE type) {
         this.type = type;
     }
 
-    public Graph(List<Vertex<T>> verticies, List<Edge<T>> edges) {
+    public Graph(Collection<Vertex<T>> verticies, Collection<Edge<T>> edges) {
         this(TYPE.UNDIRECTED, verticies, edges);
     }
 
-    public Graph(TYPE type, List<Vertex<T>> verticies, List<Edge<T>> edges) {
+    public Graph(TYPE type, Collection<Vertex<T>> verticies, Collection<Edge<T>> edges) {
         this(type);
         this.verticies.addAll(verticies);
         this.edges.addAll(edges);

src/com/jwetherell/algorithms/graph/Dijkstra.java

@@ -80,12 +80,17 @@ public static Graph.CostPathPair<Integer> getShortestPath(Graph<Integer> g, Grap
                 if (pair.getCost() == Integer.MAX_VALUE) {
                     // Haven't seen this vertex yet
                     pair.setCost(cost);
+                    // Need to remove the
+                    unvisited.remove(pair);
+                    unvisited.add(pair);
                     Set<Graph.Edge<Integer>> set = paths.get(e.getToVertex());
                     set.addAll(paths.get(e.getFromVertex()));
                     set.add(e);
                 } else if (cost < pair.getCost()) {
                     // Found a shorter path to a reachable vertex
                     pair.setCost(cost);
+                    unvisited.remove(pair);
+                    unvisited.add(pair);
                     Set<Graph.Edge<Integer>> set = paths.get(e.getToVertex());
                     set.clear();
                     set.addAll(paths.get(e.getFromVertex()));
@@ -98,8 +103,7 @@ public static Graph.CostPathPair<Integer> getShortestPath(Graph<Integer> g, Grap
                 // If we are looking for shortest path, we found it.
                 break;
             } else if (unvisited.size() > 0) {
-                // If there are other vertices to visit (which haven't been
-                // visited yet)
+                // If there are other vertices to visit (which haven't been visited yet)
                 Graph.CostVertexPair<Integer> pair = unvisited.remove();
                 vertex = pair.getVertex();
                 if (pair.getCost() == Integer.MAX_VALUE) {