fix & update: handled case of min/max element 0, fixes in tests

Author: ashokdey

src/_DataStructures_/Heaps/MaxHeap/MaxHeap.test.js

@@ -15,6 +15,11 @@ describe('MaxHeap', () => {
     expect(mh instanceof MaxHeap).toEqual(true);
   });
 
+  it('Should create a MaxHeap using collection', () => {
+    const mHBulk = new MaxHeap([1, 3, 21, 9, 101, 0]);
+    expect(mHBulk.getMax()).toEqual(101);
+  });
+
   it('Should add an element to the MaxHeap', () => {
     mh.add(10);
     expect(mh.getMax()).toEqual(10);
@@ -51,12 +56,4 @@ describe('MaxHeap', () => {
   it('Should return `null` on `remove() called on empty heap`', () => {
     expect(mh.getMax()).toEqual(null);
   });
-
-  it('Should create MaxHeap using collection : [2, 12, 0, 90]', () => {
-    const arr = [2, 12, 0, 90];
-    const mHBulk = new MaxHeap(arr);
-
-    expect(mHBulk.getMax()).toEqual(90);
-    // expect(mHBulk.()).toEqual(90);
-  });
 });

src/_DataStructures_/Heaps/MaxHeap/index.js

@@ -16,11 +16,11 @@ class MaxHeap {
   }
 
   getMax() {
-    return this.heap[0] || null;
+    return this.heap[0] !== undefined ? this.heap[0] : null;
   }
 
   remove() {
-    const max = this.heap[0] || null;
+    const max = this.heap[0] !== undefined ? this.heap[0] : null;
     // return the element at the root
     if (this.heap.length === 1) {
       this.heap.pop();

src/_DataStructures_/Heaps/MinHeap/MinHeap.test.js

@@ -0,0 +1,59 @@
+const MinHeap = require('.');
+
+describe('MinHeap', () => {
+  it('Should be a class', () => {
+    expect(typeof MinHeap.prototype.constructor).toEqual('function');
+  });
+
+  const mh = new MinHeap();
+
+  beforeEach(() => {
+    mh.destroy();
+  });
+
+  it('Should create an instance of MinHeap', () => {
+    expect(mh instanceof MinHeap).toEqual(true);
+  });
+
+  it('Should create a MinHeap using collection', () => {
+    const mHBulk = new MinHeap([112, 3, 21, 9, 10, 0]);
+    expect(mHBulk.getMin()).toEqual(0);
+  });
+
+  it('Should add an element to the MinHeap', () => {
+    mh.add(10);
+    expect(mh.getMin()).toEqual(10);
+  });
+
+  it('Should keep the smallest element at the root', () => {
+    [12, 5, 34].forEach(el => mh.add(el));
+    expect(mh.getMin()).toEqual(5);
+  });
+
+  it('Should retain Heap properties after removal of an element', () => {
+    [12, 45, 1, 34].forEach(el => mh.add(el));
+    expect(mh.getMin()).toEqual(1);
+    mh.remove();
+    expect(mh.getMin()).toEqual(12);
+  });
+
+  it('Should return `null` when heap is empty', () => {
+    [1, 34].forEach(el => mh.add(el));
+    expect(mh.getMin()).toEqual(1);
+    mh.remove();
+    mh.remove();
+    expect(mh.getMin()).toEqual(null);
+  });
+
+  it('Should return the elelment value on `remove()`', () => {
+    [1, 34].forEach(el => mh.add(el));
+    expect(mh.getMin()).toEqual(1);
+    expect(mh.remove()).toEqual(1);
+    expect(mh.remove()).toEqual(34);
+    expect(mh.getMin()).toEqual(null);
+  });
+
+  it('Should return `null` on `remove() called on empty heap`', () => {
+    expect(mh.getMin()).toEqual(null);
+  });
+});

src/_DataStructures_/Heaps/MinHeap/index.js

@@ -17,21 +17,20 @@ class MinHeap {
   }
 
   getMin() {
-    return this.heap[0] || null;
+    return this.heap[0] !== undefined ? this.heap[0] : null;
   }
 
   remove() {
-    const min = this.heap[0] || null;
-
+    const min = this.heap[0] !== undefined ? this.heap[0] : null;
+    if (this.heap.length === 1) {
+      this.heap.pop();
+    }
     if (this.heap.length > 1) {
       this.heap[0] = this.heap[this.heap.length - 1];
       this.heap.pop();
       // eslint-disable-next-line no-underscore-dangle
       this.__heapify(0);
     }
-    if (this.heap.length === 1) {
-      this.heap.pop();
-    }
     return min;
   }