some changes in generic GraphGeneric and Heap

Author: nisabmohd

src/Graphs/GraphGeneric.java

@@ -5,10 +5,17 @@
 public class GraphGeneric<T> {
 
     // example for generic graph is present in dir -> ./GenericGraphExample.java
-    Map<Object, ArrayList<Object>> map;
+    private Map<Object, ArrayList<Object>> map;
+    private boolean bidirectional;
 
     public GraphGeneric() {
         map = new HashMap<>();
+        this.bidirectional = true;
+    }
+
+    public GraphGeneric(boolean bidirectional) {
+        map = new HashMap<>();
+        this.bidirectional = bidirectional;
     }
 
     public void addEdge(T start, T end) {
@@ -23,16 +30,17 @@ public void addEdge(T start, T end) {
         if (end == null && start == null) {
             return;
         }
-        if (map.containsKey(start)) {
-            map.get(start).add(end);
-
-        } else {
-            map.put(start, new ArrayList<>(Arrays.asList(end)));
+        if (!map.containsKey(start)) {
+            map.put(start, new ArrayList<>());
+        }
+        if (!map.containsKey(end)) {
+            map.put(end, new ArrayList<>());
         }
-        if (map.containsKey(end)) {
+        if (bidirectional) {
+            map.get(start).add(end);
             map.get(end).add(start);
         } else {
-            map.put(end, new ArrayList<>(Arrays.asList(start)));
+            map.get(start).add(end);
         }
     }
 

src/Graphs/GraphGenericExample.java

@@ -22,22 +22,20 @@ public String toString() {
 public class GraphGenericExample {
 
     public static void main(String[] args) {
-        GraphGeneric<User> graph = new GraphGeneric<>();
+        GraphGeneric<User> graph = new GraphGeneric<>(false);
         User one = new User("Nisab", 05157435);
         User two = new User("Rahul", 65757567);
         User three = new User("James", 57576757);
         User four = new User("Tylor", 7575758);
 
         // Adding edge basically means making friends
         graph.addEdge(one, two);
-        graph.addEdge(one, three);
-        graph.addEdge(one, four);
+        graph.addEdge(two, three);
         graph.addEdge(three, four);
 
         System.out.println(graph);
 
         // returns friends circle of just nisab
         System.out.println(graph.dfs(one));
-
     }
 }

src/Heaps/Heap.java

@@ -99,10 +99,13 @@ public void clear() {
 
     @Override
     public String toString() {
-        StringBuilder ans = new StringBuilder("[ ");
-        for (int i = 1; i <= index; i++) {
-            ans.append(list.get(i) + " ");
+        StringBuilder ans = new StringBuilder("[");
+        if (list.size() == 1) return ans.append("]").toString();
+        int i;
+        for (i = 1; i < index; i++) {
+            ans.append(list.get(i) + ", ");
         }
+        ans.append(list.get(i));
         return ans.append("]").toString();
     }
 }