Merge pull request #1325 from mariaRoxana94/fix-error

Fixed 8XCorrectness_Bugs + 10XBad_Practice_Bugs + 14XDodgy_Code_Bugs

DataStructures/Trees/LevelOrderTraversal.java

@@ -15,8 +15,8 @@ public class LevelOrderTraversal {
     // Root of the Binary Tree
     Node root;
 
-    public LevelOrderTraversal() {
-        root = null;
+    public LevelOrderTraversal( Node root) {
+        this.root = root;
     }
 
     /* function to print level order traversal of tree*/

DataStructures/Trees/LevelOrderTraversalQueue.java

@@ -19,11 +19,9 @@ public class LevelOrderTraversalQueue {
         }
     }
 
-    Node root;
-
     /* Given a binary tree. Print its nodes in level order
      using array for implementing queue  */
-    void printLevelOrder() {
+    void printLevelOrder(Node root) {
         Queue<Node> queue = new LinkedList<Node>();
         queue.add(root);
         while (!queue.isEmpty()) {

DataStructures/Trees/ValidBSTOrNot.java

@@ -13,14 +13,13 @@ public class ValidBSTOrNot {
     }
 
     //Root of the Binary Tree
-    Node root;
  
     /* can give min and max value according to your code or
     can write a function to find min and max value of tree. */
 
     /* returns true if given search tree is binary
      search tree (efficient version) */
-    boolean isBST() {
+    boolean isBST(Node root) {
         return isBSTUtil(root, Integer.MIN_VALUE,
                 Integer.MAX_VALUE);
     }