new test

Author: amejiarosario

src/data-structures/trees/binary-search-tree.js

@@ -97,7 +97,9 @@ class BinarySearchTree {
     // Combine left and right children into one subtree without nodeToRemove
     const nodeToRemoveChildren = this.combineLeftIntoRightSubtree(nodeToRemove);
 
-    if (nodeToRemove === this.root) {
+    if (nodeToRemove.meta.multiplicity && nodeToRemove.meta.multiplicity > 1) {
+      nodeToRemove.meta.multiplicity -= 1; // handle duplicated
+    } else if (nodeToRemove === this.root) {
       // Replace (root) node to delete with the combined subtree.
       this.root = nodeToRemoveChildren;
       this.root.parent = null; // clearing up old parent

src/data-structures/trees/binary-search-tree.spec.js

@@ -231,6 +231,23 @@ describe('Binary Search Tree', () => {
 
         expect(bst.size).toBe(6);
       });
+
+      it('should remove duplicates', () => {
+        bst.add(40); // add duplicate
+        expect(n40.meta.multiplicity).toBe(2);
+
+        expect(bst.remove(40)).toBe(true);
+        expect(bst.size).toBe(7);
+        expect(n40.meta.multiplicity).toBe(1);
+        expect(bst.find(40)).toBe(n40);
+
+        expect(bst.remove(40)).toBe(true);
+        expect(bst.size).toBe(6);
+        expect(bst.find(40)).toBeFalsy();
+
+        expect(bst.remove(40)).toBe(false);
+        expect(bst.size).toBe(6);
+      });
     });
 
     describe('#bfs', () => {