ValidateBinarySearchTree: add YT link, cosmetic adjustment of naming

Author: andrei-punko

src/main/java/by/andd3dfx/tree/ValidateBinarySearchTree.java

@@ -10,6 +10,7 @@
  * Given the root of a binary tree, determine if it is a valid binary search tree (BST).
  *
  * A valid BST is defined as follows:
+ *
  *     The left of a node contains only nodes with keys strictly less than the node's key.
  *     The right subtree of a node contains only nodes with keys strictly greater than the node's key.
  *     Both the left and right subtrees must also be binary search trees.
@@ -25,6 +26,8 @@
  * Output: false
  * Explanation: The root node's value is 5 but its right child's value is 4.
  * </pre>
+ *
+ * @see <a href="https://youtu.be/KjOS_eCSaW8">Video solution</a>
  */
 public class ValidateBinarySearchTree {
 
@@ -40,14 +43,14 @@ private boolean allLessThan(int value, TreeNode node) {
         if (node == null) {
             return true;
         }
-        return node.val < value && allLessThan(value, node.left) && allLessThan(value, node.right);
+        return (node.val < value) && allLessThan(value, node.left) && allLessThan(value, node.right);
     }
 
     private boolean allGreaterThan(int value, TreeNode node) {
         if (node == null) {
             return true;
         }
-        return node.val > value && allGreaterThan(value, node.left) && allGreaterThan(value, node.right);
+        return (node.val > value) && allGreaterThan(value, node.left) && allGreaterThan(value, node.right);
     }
 
     @AllArgsConstructor

src/test/java/by/andd3dfx/tree/ValidateBinarySearchTreeTest.java

@@ -8,11 +8,11 @@
 
 public class ValidateBinarySearchTreeTest {
 
-    private ValidateBinarySearchTree binarySearchTree;
+    private ValidateBinarySearchTree validator;
 
     @Before
     public void setUp() throws Exception {
-        binarySearchTree = new ValidateBinarySearchTree();
+        validator = new ValidateBinarySearchTree();
     }
 
     @Test
@@ -21,18 +21,18 @@ public void isValidBST() {
             new TreeNode(1),
             new TreeNode(3)
         );
-        assertThat(binarySearchTree.isValidBST(root)).isTrue();
+        assertThat(validator.isValidBST(root)).isTrue();
 
         TreeNode root2 = new TreeNode(5,
             new TreeNode(1),
             new TreeNode(4, new TreeNode(3), new TreeNode(6))
         );
-        assertThat(binarySearchTree.isValidBST(root2)).isFalse();
+        assertThat(validator.isValidBST(root2)).isFalse();
 
         TreeNode root3 = new TreeNode(5,
             new TreeNode(1),
             new TreeNode(7, new TreeNode(6), new TreeNode(9))
         );
-        assertThat(binarySearchTree.isValidBST(root3)).isTrue();
+        assertThat(validator.isValidBST(root3)).isTrue();
     }
 }