Add deleteByValue to circular linked list and expose in CLI menu

Data-Structures/Linked-Lists/CircularLinkedLists.java

@@ -59,11 +59,11 @@ public void deleteFromBeginning() {
         }
     }
 
-    public void deleteFromEnd() {
-        if (tail == null) {
-            System.out.println("List is Empty. Can't Delete.");
-            return;
-        }
+    public void deleteFromEnd() {
+        if (tail == null) {
+            System.out.println("List is Empty. Can't Delete.");
+            return;
+        }
 
         Node head = tail.next;
 
@@ -79,9 +79,51 @@ public void deleteFromEnd() {
         }
 
         System.out.println(tail.data + " Deleted from End.");
-        temp.next = tail.next;
-        tail = temp;
-    }
+        temp.next = tail.next;
+        tail = temp;
+    }
+
+    public void deleteByValue(int key) {
+        if (tail == null) {
+            System.out.println("List is Empty. Can't Delete.");
+            return;
+        }
+
+        Node head = tail.next;
+
+        if (head == tail) {
+            if (head.data == key) {
+                System.out.println(key + " Deleted from List.");
+                tail = null;
+            } else {
+                System.out.println("Element " + key + " NOT Found!");
+            }
+            return;
+        }
+
+        Node prev = tail;
+        Node current = head;
+        do {
+            if (current.data == key) {
+                prev.next = current.next;
+
+                if (current == tail) {
+                    tail = prev;
+                }
+
+                if (current == head) {
+                    tail.next = current.next;
+                }
+
+                System.out.println(key + " Deleted from List.");
+                return;
+            }
+            prev = current;
+            current = current.next;
+        } while (current != head);
+
+        System.out.println("Element " + key + " NOT Found!");
+    }
 
     public void display() {
         if (tail == null) {
@@ -128,11 +170,12 @@ public static void main(String[] args) {
             System.out.println("1. Insert at Beginning");
             System.out.println("2. Insert at End");
             System.out.println("3. Delete from Beginning");
-            System.out.println("4. Delete from End");
-            System.out.println("5. Search");
-            System.out.println("6. Display");
-            System.out.println("7. Exit");
-            System.out.print("Enter your choice: ");
+            System.out.println("4. Delete from End");
+            System.out.println("5. Delete by Value");
+            System.out.println("6. Search");
+            System.out.println("7. Display");
+            System.out.println("8. Exit");
+            System.out.print("Enter your choice: ");
 
             choice = sc.nextInt();
 
@@ -157,25 +200,59 @@ public static void main(String[] args) {
                     cll.deleteFromEnd();
                     break;
 
-                case 5:
-                    System.out.print("Enter element to Search: ");
-                    int key = sc.nextInt();
-                    cll.search(key);
-                    break;
-
-                case 6:
-                    cll.display();
-                    break;
-
-                case 7:
-                    System.out.println("Exiting...");
-                    break;
+                case 5:
+                    System.out.print("Enter element to Delete: ");
+                    int deleteKey = sc.nextInt();
+                    cll.deleteByValue(deleteKey);
+                    break;
+
+                case 6:
+                    System.out.print("Enter element to Search: ");
+                    int key = sc.nextInt();
+                    cll.search(key);
+                    break;
+
+                case 7:
+                    cll.display();
+                    break;
+
+                case 8:
+                    System.out.println("Exiting...");
+                    break;
 
                 default:
                     System.out.println("Invalid choice!");
             }
-        } while (choice != 7);
-
-        sc.close();
-    }
-}
+        } while (choice != 8);
+
+        sc.close();
+    }
+}
+
+/*
+Sample Output:
+
+--- Circular Linked List Operations Menu ---
+1. Insert at Beginning
+2. Insert at End
+3. Delete from Beginning
+4. Delete from End
+5. Delete by Value
+6. Search
+7. Display
+8. Exit
+Enter your choice: 2
+Enter element to Insert at End: 10
+10 Inserted at the End.
+
+Enter your choice: 2
+Enter element to Insert at End: 20
+20 Inserted at the End.
+
+Enter your choice: 5
+Enter element to Delete: 10
+10 Deleted from List.
+
+Enter your choice: 7
+20 -> (head)
+*/