Code cleanup (#4246)

src/main/java/com/thealgorithms/datastructures/graphs/TarjansAlgorithm.java

@@ -1,7 +1,6 @@
 package com.thealgorithms.datastructures.graphs;
 
 import java.util.ArrayList;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Stack;
 

src/main/java/com/thealgorithms/datastructures/lists/DoublyLinkedList.java

@@ -28,18 +28,12 @@ public class DoublyLinkedList {
      */
     private LinkOperations linkOperations;
 
-    /**
-     * Size refers to the number of elements present in the list
-     */
-    private int size;
-
     /**
      * Default Constructor
      */
     public DoublyLinkedList() {
         head = null;
         tail = null;
-        size = 0;
     }
 
     /**
@@ -55,7 +49,6 @@ public class DoublyLinkedList {
         for (int i : array) {
             linkOperations.insertTail(i, this);
         }
-        size = array.length;
     }
 
     /**

src/main/java/com/thealgorithms/datastructures/lists/Merge_K_SortedLinkedlist.java

@@ -47,10 +47,5 @@ public class Merge_K_SortedLinkedlist {
 
         private int data;
         private Node next;
-
-        public Node(int d) {
-            this.data = d;
-            next = null;
-        }
     }
 }

src/main/java/com/thealgorithms/datastructures/lists/SinglyLinkedList.java

@@ -148,9 +148,7 @@ public class SinglyLinkedList extends Node {
     public void clear() {
         Node cur = head;
         while (cur != null) {
-            Node prev = cur;
             cur = cur.next;
-            prev = null; // clear to let GC do its work
         }
         head = null;
         size = 0;
@@ -346,9 +344,7 @@ public class SinglyLinkedList extends Node {
     public void deleteNth(int position) {
         checkBounds(position, 0, size - 1);
         if (position == 0) {
-            Node destroy = head;
             head = head.next;
-            destroy = null;
             /* clear to let GC do its work */
             size--;
             return;
@@ -358,10 +354,7 @@ public class SinglyLinkedList extends Node {
             cur = cur.next;
         }
 
-        Node destroy = cur.next;
         cur.next = cur.next.next;
-        destroy = null; // clear to let GC do its work
-
         size--;
     }
 

src/main/java/com/thealgorithms/datastructures/stacks/NodeStack.java

@@ -43,7 +43,6 @@ public class NodeStack<Item> {
     private Item data;
 
     private static NodeStack<?> head;
-    private NodeStack<?> next;
     private NodeStack<?> previous;
     private static int size = 0;
 
@@ -72,7 +71,7 @@ public class NodeStack<Item> {
         } else {
             newNs.setPrevious(NodeStack.head);
             NodeStack.head.setNext(newNs);
-            NodeStack.head.setHead(newNs);
+            NodeStack.setHead(newNs);
         }
 
         NodeStack.setSize(NodeStack.getSize() + 1);
@@ -86,7 +85,7 @@ public class NodeStack<Item> {
     public Item pop() {
         Item item = (Item) NodeStack.head.getData();
 
-        NodeStack.head.setHead(NodeStack.head.getPrevious());
+        NodeStack.setHead(NodeStack.head.getPrevious());
         NodeStack.head.setNext(null);
 
         NodeStack.setSize(NodeStack.getSize() - 1);
@@ -133,23 +132,11 @@ public class NodeStack<Item> {
         }
     }
 
-    /**
-     * Getters and setters (private)
-     */
-    private NodeStack<?> getHead() {
-        return NodeStack.head;
-    }
-
     private static void setHead(NodeStack<?> ns) {
         NodeStack.head = ns;
     }
 
-    private NodeStack<?> getNext() {
-        return next;
-    }
-
     private void setNext(NodeStack<?> next) {
-        this.next = next;
     }
 
     private NodeStack<?> getPrevious() {
@@ -171,8 +158,4 @@ public class NodeStack<Item> {
     private Item getData() {
         return this.data;
     }
-
-    private void setData(Item item) {
-        this.data = item;
-    }
 }

src/main/java/com/thealgorithms/datastructures/trees/GenericTree.java

@@ -23,8 +23,6 @@ public class GenericTree {
     }
 
     private Node root;
-    private int size;
-
     public GenericTree() { // Constructor
         Scanner scn = new Scanner(System.in);
         root = create_treeG(null, 0, scn);
@@ -44,7 +42,6 @@ public class GenericTree {
         int number = scn.nextInt();
         for (int i = 0; i < number; i++) {
             Node child = create_treeG(node, i, scn);
-            size++;
             node.child.add(child);
         }
         return node;

src/main/java/com/thealgorithms/datastructures/trees/TreeRandomNode.java

@@ -30,11 +30,6 @@ public class TreeRandomNode {
 
         int item;
         Node left, right;
-
-        public Node(int key) {
-            item = key;
-            left = right = null;
-        }
     }
 
     // Using an arraylist to store the inorder traversal of the given binary tree

src/main/java/com/thealgorithms/datastructures/trees/nearestRightKey.java

@@ -12,6 +12,7 @@ class Main {
         int inputX0 = sc.nextInt();
         int toPrint = nearestRightKey(root, inputX0);
         System.out.println("Key: " + toPrint);
+        sc.close();
     }
 
     public static NRKTree BuildTree() {