Fix incorrect file extension (Fixes: TheAlgorithms#2716) (TheAlgorithms#2717)

shivamshrey · web-flow · commit 9b90628a89d2 · 2021-10-27T21:56:00.000+03:00
diff --git a/DataStructures/Lists/CreateAndDetectLoop.java b/DataStructures/Lists/CreateAndDetectLoop.java
@@ -0,0 +1,95 @@
+package DataStructures.Lists;
+
+import java.util.Scanner;
+
+public class CreateAndDetectLoop {
+
+	/**
+	 * Prints the linked list.
+	 * 
+	 * @param	head	head node of the linked list
+	 */
+	static void printList(Node head) {		
+        Node cur = head;
+        
+        while (cur != null) {
+            System.out.print(cur.value + " ");
+            cur = cur.next;
+        }
+    }
+
+	/**
+	 * Creates a loop in the linked list.
+	 * @see 	<a href="https://www.geeksforgeeks.org/make-loop-k-th-position-linked-list/">
+	 * 			GeeksForGeeks: Make a loop at K-th position</a>
+	 * @param	head	head node of the linked list
+	 * @param	k		position of node where loop is to be created
+	 */
+    static void createLoop(Node head, int k) {
+    	if (head == null)
+    		return;
+        Node temp = head;
+        int count = 1;
+        while (count < k) { 		// Traverse the list till the kth node
+            temp = temp.next;
+            count++;
+        }
+
+        Node connectedPoint = temp;
+
+        while (temp.next != null) 	// Traverse remaining nodes
+            temp = temp.next;
+
+        temp.next = connectedPoint; // Connect last node to k-th element
+    }
+
+    /**
+	 * Detects the presence of a loop in the linked list.
+	 * @see 	<a href="https://en.wikipedia.org/wiki/Cycle_detection#Floyd's_tortoise_and_hare">
+	 * 			Floyd's Cycle Detection Algorithm</a>
+	 * 
+	 * @param 	head 	the head node of the linked list
+	 * 
+	 * @return 		 	true if loop exists else false
+	 */
+    static boolean detectLoop(Node head) {
+    	Node sptr = head;
+    	Node fptr = head;
+    	
+    	while (fptr != null && fptr.next != null) {
+    		sptr = sptr.next;
+    		fptr = fptr.next.next;
+    		if (fptr == sptr)
+    			return true;
+    	}
+    	
+    	return false;
+    }
+
+    public static void main(String[] args) {
+        SinglyLinkedList singlyLinkedList = new SinglyLinkedList();
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("Enter the number of elements to be inserted: ");
+        int n = sc.nextInt();
+        System.out.printf("Enter the %d elements: \n", n);
+        while (n-- > 0)
+        	singlyLinkedList.insert(sc.nextInt());
+        
+        System.out.print("Given list: ");
+        printList(singlyLinkedList.getHead());
+        System.out.println();
+        
+        System.out.println("Enter the location to generate loop: ");
+        int k = sc.nextInt();
+        
+        createLoop(singlyLinkedList.getHead(), k);
+        
+        if (detectLoop(singlyLinkedList.getHead()))
+            System.out.println("Loop found");
+        else
+            System.out.println("No loop found");
+        
+        sc.close();
+    }
+}
diff --git a/DataStructures/Lists/README.md b/DataStructures/Lists/README.md
@@ -25,6 +25,6 @@ The `next` variable points to the next node in the data structure and value stor
 1. `CircleLinkedList.java` : A circular linked list where next pointer of last node points to first nide of linked list.
 2. `SinglyLinkedList.java` : The classic case of single links.
 3. `CountSinglyLinkedListRecursion.java`: Recursively counts the size of a list.
-4. `detect_and_create_loop.java` : Detect a loop in linked list
+4. `CreateAndDetectLoop.java` : Create and detect a loop in a linked list.
 5. `DoublyLinkedList.java` : A modification of singly linked list which has a `prev` pointer to point to the previous node.
 6. `Merge_K_SortedLinkedlist.java` : Merges K sorted linked list with mergesort (mergesort is also the most efficient sorting algorithm for linked list).
diff --git a/DataStructures/Lists/detect_and_create_loop.jav b/DataStructures/Lists/detect_and_create_loop.jav
