Merge pull request mgechev#100 from krzysztof-grzybek/master

Fix heap

Author: mgechev

src/data-structures/heap.js

@@ -82,7 +82,8 @@
     }
 
     if (right < this._heap.length &&
-        this._cmp(this._heap[right], this._heap[index]) > 0) {
+        this._cmp(this._heap[right], this._heap[index]) > 0 &&
+        this._cmp(this._heap[right], this._heap[left]) > 0) {
       extr = right;
     }
 
@@ -116,6 +117,7 @@
         index = parent;
         parent = Math.floor(parent / 2);
       }
+      this._heapify(index);
     }
     return parent;
   };

test/data-structures/heap.spec.js

@@ -58,4 +58,38 @@ describe('Heap', function () {
     res = heap.extract();
     expect(res).toBe(66);
   });
+  it('should update top node properly', function () {
+    var heap = new Heap(function (a, b) {
+      return a.val - b.val;
+    });
+    var objectToUpdate = { val: 66 };
+    heap.add(objectToUpdate);
+    heap.add({ val: 11 });
+    heap.add({ val: 55 });
+    objectToUpdate.val = 0;
+    heap.update(objectToUpdate);
+    var res = heap.extract();
+    expect(res.val).toBe(55);
+    res = heap.extract();
+    expect(res.val).toBe(11);
+    res = heap.extract();
+    expect(res.val).toBe(0);
+  });
+  it('should update bottom node properly', function () {
+    var heap = new Heap(function (a, b) {
+      return a.val - b.val;
+    });
+    var objectToUpdate = { val: 0 };
+    heap.add(objectToUpdate);
+    heap.add({ val: 11 });
+    heap.add({ val: 55 });
+    objectToUpdate.val = 66;
+    heap.update(objectToUpdate);
+    var res = heap.extract();
+    expect(res.val).toBe(66);
+    res = heap.extract();
+    expect(res.val).toBe(55);
+    res = heap.extract();
+    expect(res.val).toBe(11);
+  });
 });