Code cleanup (#4246)

src/main/java/com/thealgorithms/conversions/OctalToBinary.java

@@ -1,5 +1,4 @@
 package com.thealgorithms.conversions;
-import java.util.Scanner;
 
 /**
  * Converts any Octal Number to a Binary Number

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() {

src/main/java/com/thealgorithms/dynamicprogramming/LongestValidParentheses.java

@@ -1,7 +1,5 @@
 package com.thealgorithms.dynamicprogramming;
 
-import java.util.Scanner;
-
 /**
  * Given a string containing just the characters '(' and ')', find the length of
  * the longest valid (well-formed) parentheses substring.

src/main/java/com/thealgorithms/maths/DeterminantOfMatrix.java

@@ -51,5 +51,6 @@ public class DeterminantOfMatrix {
             }
         }
         System.out.println(determinant(a, n));
+        in.close();
     }
 }

src/main/java/com/thealgorithms/maths/DudeneyNumber.java

@@ -6,8 +6,6 @@
  */
 package com.thealgorithms.maths;
 
-import java.io.*;
-
 public class DudeneyNumber {
 
     // returns True if the number is a Dudeney number and False if it is not a Dudeney number.

src/main/java/com/thealgorithms/maths/KeithNumber.java

@@ -49,5 +49,6 @@ class KeithNumber {
         } else {
             System.out.println("No, the given number is not a Keith number.");
         }
+        in.close();
     }
 }

src/main/java/com/thealgorithms/maths/LeastCommonMultiple.java

@@ -21,6 +21,7 @@ public class LeastCommonMultiple {
         System.out.println("Please enter second number >> ");
         int num2 = input.nextInt();
         System.out.println("The least common multiple of two numbers is >> " + lcm(num1, num2));
+        input.close();
     }
 
     /*

src/main/java/com/thealgorithms/maths/MagicSquare.java

@@ -45,5 +45,6 @@ public class MagicSquare {
             }
             System.out.println();
         }
+        sc.close();
     }
 }

src/main/java/com/thealgorithms/maths/NonRepeatingElement.java

@@ -50,6 +50,7 @@ public class NonRepeatingElement {
         }
 
         System.out.println("The two non repeating elements are " + num1 + " and " + num2);
+        sc.close();
     }
     /*
   Explanation of the code:

src/main/java/com/thealgorithms/maths/SquareRootWithNewtonRaphsonMethod.java

@@ -1,7 +1,5 @@
 package com.thealgorithms.maths;
 
-import java.util.Scanner;
-
 /*
  *To learn about the method, visit the link below :
  * https://en.wikipedia.org/wiki/Newton%27s_method

src/main/java/com/thealgorithms/minimizinglateness/MinimizingLateness.java

@@ -11,9 +11,6 @@ public class MinimizingLateness {
 
         int t = 0; // Time required for the operation to be performed
         int d = 0; // Time the job should be completed
-        int s = 0; // Start time of the task
-        int f = 0; // End time of the operation
-
         public Schedule(int t, int d) {
             this.t = t;
             this.d = d;
@@ -46,8 +43,6 @@ public class MinimizingLateness {
         int tryTime = 0; // Total time worked
         int lateness = 0; // Lateness
         for (int j = 0; j < indexCount - 1; j++) {
-            array[j].s = tryTime; // Start time of the task
-            array[j].f = tryTime + array[j].t; // Time finished
             tryTime = tryTime + array[j].t; // Add total work time
             // Lateness
             lateness = lateness + Math.max(0, tryTime - array[j].d);

src/main/java/com/thealgorithms/misc/Sort012D.java

@@ -21,6 +21,7 @@ public class Sort012D {
             a[i] = np.nextInt();
         }
         sort012(a);
+        np.close();
     }
 
     public static void sort012(int[] a) {

src/main/java/com/thealgorithms/misc/Sparcity.java

@@ -49,5 +49,6 @@ class Sparcity {
             }
         }
         System.out.println("Sparcity of matrix is: " + sparcity(mat));
+        in.close();
     }
 }

src/main/java/com/thealgorithms/misc/ThreeSumProblem.java

@@ -19,6 +19,7 @@ public class ThreeSumProblem {
         System.out.println("Brute Force Approach\n" + (th.BruteForce(arr, ts)) + "\n");
         System.out.println("Two Pointer Approach\n" + (th.TwoPointer(arr, ts)) + "\n");
         System.out.println("Hashmap Approach\n" + (th.Hashmap(arr, ts)));
+        scan.close();
     }
 
     public List<List<Integer>> BruteForce(int[] nums, int target) {

src/main/java/com/thealgorithms/others/BoyerMoore.java

@@ -44,5 +44,6 @@ public class BoyerMoore {
             a[i] = input.nextInt();
         }
         System.out.println("the majority element is " + findmajor(a));
+        input.close();
     }
 }

src/main/java/com/thealgorithms/others/CountWords.java

@@ -1,7 +1,5 @@
 package com.thealgorithms.others;
 
-import java.util.Scanner;
-
 /**
  * @author Marcus
  */

src/main/java/com/thealgorithms/others/HappyNumbersSeq.java

@@ -19,6 +19,7 @@ public class HappyNumbersSeq {
         }
         String res = n == 1 ? "1 Happy number" : "Sad number";
         System.out.println(res);
+        in.close();
     }
 
     private static int sumSquares(int n) {

src/main/java/com/thealgorithms/others/Huffman.java

@@ -118,5 +118,6 @@ public class Huffman {
 
         // print the codes by traversing the tree
         printCode(root, "");
+        s.close();
     }
 }

src/main/java/com/thealgorithms/others/RotateMatriceBy90Degree.java

@@ -22,8 +22,7 @@ class Rotate_by_90_degree {
                 }
             }
 
-            Rotate g = new Rotate();
-            g.rotate(arr);
+            Rotate.rotate(arr);
             printMatrix(arr);
         }
         sc.close();

src/main/java/com/thealgorithms/others/cn/HammingDistance.java

@@ -1,8 +1,5 @@
 package com.thealgorithms.others.cn;
 
-import java.util.ArrayList;
-import java.util.List;
-
 final public class HammingDistance {
     private HammingDistance() {
     }

src/main/java/com/thealgorithms/searches/LinearSearchThread.java

@@ -33,6 +33,7 @@ public class LinearSearchThread {
         }
         boolean found = t.getResult() || t1.getResult() || t2.getResult() || t3.getResult();
         System.out.println("Found = " + found);
+        in.close();
     }
 }
 

src/main/java/com/thealgorithms/searches/PerfectBinarySearch.java

@@ -21,9 +21,8 @@ class PerfectBinarySearch {
     }
 
     public static void main(String[] args) {
-        PerfectBinarySearch BinarySearch = new PerfectBinarySearch();
         int[] array = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
-        assert BinarySearch.binarySearch(array, -1) == -1;
-        assert BinarySearch.binarySearch(array, 11) == -1;
+        assert PerfectBinarySearch.binarySearch(array, -1) == -1;
+        assert PerfectBinarySearch.binarySearch(array, 11) == -1;
     }
 }

src/main/java/com/thealgorithms/searches/SearchInARowAndColWiseSortedMatrix.java

@@ -1,7 +1,5 @@
 package com.thealgorithms.searches;
 
-import java.util.Arrays;
-
 public class SearchInARowAndColWiseSortedMatrix {
     /**
      * Search a key in row and column wise sorted matrix

src/main/java/com/thealgorithms/searches/SquareRootBinarySearch.java

@@ -27,6 +27,7 @@ public class SquareRootBinarySearch {
         int num = sc.nextInt();
         long ans = squareRoot(num);
         System.out.println("The square root is : " + ans);
+        sc.close();
     }
 
     /**

src/main/java/com/thealgorithms/searches/sortOrderAgnosticBinarySearch.java

@@ -1,5 +1,4 @@
 package com.thealgorithms.searches;
-import java.util.*;
 public class sortOrderAgnosticBinarySearch {
     public static int find(int[] arr, int key) {
         int start = 0;

src/main/java/com/thealgorithms/sorts/MergeSortNoExtraSpace.java

@@ -66,5 +66,6 @@ public class MergeSortNoExtraSpace {
         for (int i = 0; i < a.length; i++) {
             System.out.print(a[i] + " ");
         }
+        inp.close();
     }
 }

src/main/java/com/thealgorithms/sorts/TopologicalSort.java

@@ -33,22 +33,6 @@ public class TopologicalSort {
          * */
         public final String label;
 
-        /*
-         * Weight of vertex
-         * (more accurately defined as the time that a vertex has begun a visit in DFS)
-         * */
-        public int weight;
-
-        /*
-         * The time that the vertex has finished a visit in DFS
-         * */
-        public int finished;
-
-        /*
-         * π parent of the vertex
-         * */
-        public Vertex predecessor;
-
         /*
          * Represents the category of visit in DFS
          * */
@@ -90,11 +74,6 @@ public class TopologicalSort {
         }
     }
 
-    /*
-     * Time variable in DFS
-     * */
-    private static int time;
-
     /*
      * Depth First Search
      *
@@ -135,12 +114,9 @@ public class TopologicalSort {
      *   u.f = time
      * */
     private static String sort(Graph graph, Vertex u, LinkedList<String> list) {
-        time++;
-        u.weight = time;
         u.color = Color.GRAY;
         graph.adj.get(u.label).next.forEach(label -> {
             if (graph.adj.get(label).color == Color.WHITE) {
-                graph.adj.get(label).predecessor = u;
                 list.addFirst(sort(graph, graph.adj.get(label), list));
             } else if (graph.adj.get(label).color == Color.GRAY) {
                 /*
@@ -153,8 +129,6 @@ public class TopologicalSort {
             }
         });
         u.color = Color.BLACK;
-        time++;
-        u.finished = time;
         return u.label;
     }
 }

src/main/java/com/thealgorithms/strings/LongestPalindromicSubstring.java

@@ -12,6 +12,7 @@ class LongestPalindromicSubstring {
         System.out.print("Enter the string: ");
         str = sc.nextLine();
         System.out.println("Longest substring is : " + s.longestPalindrome(str));
+        sc.close();
     }
 }
 

src/main/java/com/thealgorithms/strings/WordLadder.java

@@ -1,6 +1,5 @@
 package com.thealgorithms.strings;
 
-import java.util.Arrays;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;