Added Vertex with Adjacent Vertices,Added Edge List with Respective W…

…eights And Finally implemented Dijkstra's Algorithm

Graph.iml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

src/EdgeArrayList.java

@@ -0,0 +1,24 @@
+import java.util.ArrayList;
+public class EdgeArrayList {
+    private class EdgeArrayListNode {
+        Vertex a,b;
+        int weight;
+        public EdgeArrayListNode(Vertex a,Vertex b,int weight){
+            this.a = a;
+            this.b = b;
+            this.weight = weight;
+        }
+    }
+    ArrayList<EdgeArrayListNode> edgeArrayList = new ArrayList<>();
+    public void addEdge(Vertex s,Vertex d,int w){
+        edgeArrayList.add(new EdgeArrayListNode(s,d,w));
+    }
+    public int getWeight(Vertex s,Vertex d){
+        for (EdgeArrayListNode node : edgeArrayList){
+            if ((node.a.name == s.name) && (node.b.name==d.name)){
+                return node.weight;
+            }
+        }
+        return -1;
+    }
+}

src/Main.java

@@ -1,5 +1,58 @@
+import java.util.Comparator;
+import java.util.PriorityQueue;
 public class Main {
     public static void main(String[] args) {
-        System.out.println("Hello world!");
+        Vertex A = new Vertex('A');
+        Vertex B = new Vertex('B');
+        Vertex C = new Vertex('C');
+        Vertex D = new Vertex('D');
+        Vertex E = new Vertex('E');
+
+        A.adjacentVertices.add(B);
+        A.adjacentVertices.add(C);
+        B.adjacentVertices.add(E);
+        C.adjacentVertices.add(B);
+        C.adjacentVertices.add(D);
+        D.adjacentVertices.add(E);
+
+        EdgeArrayList edgeArrayList = new EdgeArrayList();
+        edgeArrayList.addEdge(A,B,4);
+        edgeArrayList.addEdge(A,C,1);
+        edgeArrayList.addEdge(B,E,4);
+        edgeArrayList.addEdge(C,B,2);
+        edgeArrayList.addEdge(C,D,4);
+        edgeArrayList.addEdge(D,E,4);
+
+        DijkstraAlgo(A,E,edgeArrayList);
+    }
+    public static void DijkstraAlgo(Vertex source,Vertex destination,EdgeArrayList edgeArrayList){
+        PriorityQueue<Vertex> priorityQueue = new PriorityQueue<>(Comparator.comparingInt(o -> o.pathDistanceFromSourceVertex));
+        source.pathAdjacentSourceVertex = source;
+        source.pathDistanceFromSourceVertex = 0;
+        priorityQueue.add(source);
+        while(!priorityQueue.isEmpty()){
+            Vertex c = priorityQueue.remove();
+            if (c.explored){continue;}
+            for (Vertex adj : c.adjacentVertices){
+                if (adj.explored){continue;}
+                if (adj.pathDistanceFromSourceVertex>(c.pathDistanceFromSourceVertex + edgeArrayList.getWeight(c,adj))){
+                    adj.pathDistanceFromSourceVertex = c.pathDistanceFromSourceVertex + edgeArrayList.getWeight(c,adj);
+                    adj.pathAdjacentSourceVertex = c;
+                }
+                priorityQueue.add(adj);
+            }
+            c.explored = true;
+        }
+
+        // Printing the Shortest Path
+        Vertex c = destination;
+        StringBuilder path = new StringBuilder(c.name + "(Cost to reach here " + destination.pathDistanceFromSourceVertex +") <- ");
+        c = c.pathAdjacentSourceVertex;
+        while (c.name != source.name){
+            path.append(c.name).append(" <- ");
+            c = c.pathAdjacentSourceVertex;
+        }
+        path.append(c.name);
+        System.out.println(path);
     }
 }

src/Vertex.java

@@ -0,0 +1,15 @@
+import java.util.ArrayList;
+public class Vertex {
+    char name;
+    boolean explored;
+    int pathDistanceFromSourceVertex;
+    ArrayList<Vertex> adjacentVertices;
+    Vertex pathAdjacentSourceVertex;
+    public Vertex (char name){
+        this.name = name;
+        explored = false;
+        pathDistanceFromSourceVertex = Integer.MAX_VALUE;
+        adjacentVertices = new ArrayList<>();
+        pathAdjacentSourceVertex = null;
+    }
+}