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Update MaxHeapAdhoc.js #1460

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Update MaxHeapAdhoc.js #1460

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54 changes: 23 additions & 31 deletions src/data-structures/heap/MaxHeapAdhoc.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,8 @@
class MaxHeapAdhoc {
constructor(heap = []) {
this.heap = [];
heap.forEach(this.add);
// Use an arrow function to maintain context for 'this'.
heap.forEach(num => this.add(num));
}

add(num) {
Expand All @@ -16,15 +17,17 @@ class MaxHeapAdhoc {
}

peek() {
return this.heap[0];
return this.isEmpty() ? undefined : this.heap[0];
}

poll() {
if (this.heap.length === 0) return undefined;
if (this.isEmpty()) return undefined;
const top = this.heap[0];
this.heap[0] = this.heap[this.heap.length - 1];
this.heap.pop();
this.heapifyDown();
const last = this.heap.pop(); // Remove the last element to replace the top
if (!this.isEmpty()) {
this.heap[0] = last; // Move the last element to the root
this.heapifyDown(); // Re-establish the heap property
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Why do we explicitly check? !this.isEmpty() here at line no 27 as we are returning undefined if this.isEmpty() is true.
So the lines 25 to 29 will execute only if !this.isEmpty() is true. This check is redundant here.

}
return top;
}

Expand All @@ -49,31 +52,22 @@ class MaxHeapAdhoc {
heapifyDown() {
let nodeIndex = 0;

while (
(
this.hasLeftChild(nodeIndex) && this.heap[nodeIndex] < this.leftChild(nodeIndex)
)
|| (
this.hasRightChild(nodeIndex) && this.heap[nodeIndex] < this.rightChild(nodeIndex)
)
) {
while (this.hasLeftChild(nodeIndex)) {
const leftIndex = this.getLeftChildIndex(nodeIndex);
const rightIndex = this.getRightChildIndex(nodeIndex);
const left = this.leftChild(nodeIndex);
const right = this.rightChild(nodeIndex);

if (this.hasLeftChild(nodeIndex) && this.hasRightChild(nodeIndex)) {
if (left >= right) {
this.swap(leftIndex, nodeIndex);
nodeIndex = leftIndex;
} else {
this.swap(rightIndex, nodeIndex);
nodeIndex = rightIndex;
}
} else if (this.hasLeftChild(nodeIndex)) {
this.swap(leftIndex, nodeIndex);
nodeIndex = leftIndex;
let largerChildIndex = leftIndex;

// Check if the right child exists and is greater than the left child
if (this.hasRightChild(nodeIndex) && this.rightChild(nodeIndex) > this.leftChild(nodeIndex)) {
largerChildIndex = rightIndex;
}

// If the current node is greater than the largest child, break
if (this.heap[nodeIndex] >= this.heap[largerChildIndex]) break;

// Swap with the larger child
this.swap(nodeIndex, largerChildIndex);
nodeIndex = largerChildIndex;
}
}

Expand Down Expand Up @@ -106,9 +100,7 @@ class MaxHeapAdhoc {
}

swap(indexOne, indexTwo) {
const tmp = this.heap[indexTwo];
this.heap[indexTwo] = this.heap[indexOne];
this.heap[indexOne] = tmp;
[this.heap[indexOne], this.heap[indexTwo]] = [this.heap[indexTwo], this.heap[indexOne]];
}
}

Expand Down