@@ -47,7 +47,7 @@ export default class Heap {
4747 * @return {boolean }
4848 */
4949 hasParent ( childIndex ) {
50- return this . getParentIndex ( childIndex ) >= 0 ;
50+ return childIndex > 0 ;
5151 }
5252
5353 /**
@@ -144,17 +144,16 @@ export default class Heap {
144144
145145 /**
146146 * @param {* } item
147- * @param {Comparator } [customFindingComparator ]
147+ * @param {Comparator } [customComparator ]
148148 * @return {Heap }
149149 */
150- remove ( item , customFindingComparator ) {
150+ remove ( item , customComparator = this . compare ) {
151151 // Find number of items to remove.
152- const customComparator = customFindingComparator || this . compare ;
153152 const numberOfItemsToRemove = this . find ( item , customComparator ) . length ;
154153
155154 for ( let iteration = 0 ; iteration < numberOfItemsToRemove ; iteration += 1 ) {
156155 // We need to find item index to remove each time after removal since
157- // indices are being change after each heapify process.
156+ // indices are being changed after each heapify process.
158157 const indexToRemove = this . find ( item , customComparator ) . pop ( ) ;
159158
160159 // If we need to remove last child in the heap then just remove it.
@@ -165,16 +164,14 @@ export default class Heap {
165164 // Move last element in heap to the vacant (removed) position.
166165 this . heapContainer [ indexToRemove ] = this . heapContainer . pop ( ) ;
167166
168- // Get parent.
169- const parentItem = this . hasParent ( indexToRemove ) ? this . parent ( indexToRemove ) : null ;
170- const leftChild = this . hasLeftChild ( indexToRemove ) ? this . leftChild ( indexToRemove ) : null ;
167+ const parentItem = this . parent ( indexToRemove ) ;
171168
172- // If there is no parent or parent is in incorrect order with the node
169+ // If there is no parent or parent is in correct order with the node
173170 // we're going to delete then heapify down. Otherwise heapify up.
174171 if (
175- leftChild !== null
172+ this . hasLeftChild ( indexToRemove )
176173 && (
177- parentItem === null
174+ parentItem == null
178175 || this . pairIsInCorrectOrder ( parentItem , this . heapContainer [ indexToRemove ] )
179176 )
180177 ) {
@@ -193,12 +190,11 @@ export default class Heap {
193190 * @param {Comparator } [customComparator]
194191 * @return {Number[] }
195192 */
196- find ( item , customComparator ) {
193+ find ( item , customComparator = this . compare ) {
197194 const foundItemIndices = [ ] ;
198- const comparator = customComparator || this . compare ;
199195
200196 for ( let itemIndex = 0 ; itemIndex < this . heapContainer . length ; itemIndex += 1 ) {
201- if ( comparator . equal ( item , this . heapContainer [ itemIndex ] ) ) {
197+ if ( customComparator . equal ( item , this . heapContainer [ itemIndex ] ) ) {
202198 foundItemIndices . push ( itemIndex ) ;
203199 }
204200 }
@@ -224,9 +220,9 @@ export default class Heap {
224220 * @param {number } [customStartIndex]
225221 */
226222 heapifyUp ( customStartIndex ) {
227- // Take last element (last in array or the bottom left in a tree) in
228- // a heap container and lift him up until we find the parent element
229- // that is less then the current new one .
223+ // Take the last element (last in array or the bottom left in a tree)
224+ // in the heap container and lift it up until it is in the correct
225+ // order with respect to its parent element .
230226 let currentIndex = customStartIndex || this . heapContainer . length - 1 ;
231227
232228 while (
@@ -241,10 +237,11 @@ export default class Heap {
241237 /**
242238 * @param {number } [customStartIndex]
243239 */
244- heapifyDown ( customStartIndex ) {
245- // Compare the root element to its children and swap root with the smallest
246- // of children. Do the same for next children after swap.
247- let currentIndex = customStartIndex || 0 ;
240+ heapifyDown ( customStartIndex = 0 ) {
241+ // Compare the parent element to its children and swap parent with the appropriate
242+ // child (smallest child for MinHeap, largest child for MaxHeap).
243+ // Do the same for next children after swap.
244+ let currentIndex = customStartIndex ;
248245 let nextIndex = null ;
249246
250247 while ( this . hasLeftChild ( currentIndex ) ) {
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