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@ankitamasand
Last active Dec 10, 2021
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class MinHeap {
constructor () {
/* Initialing the array heap and adding a dummy element at index 0 */
this.heap = [null]
}
getMin () {
/* Accessing the min element at index 1 in the heap array */
return this.heap[1]
}
insert (node) {
/* Inserting the new node at the end of the heap array */
this.heap.push(node)
/* Finding the correct position for the new node */
if (this.heap.length > 1) {
let current = this.heap.length - 1
/* Traversing up the parent node until the current node (current) is greater than the parent (current/2)*/
while (current > 1 && this.heap[Math.floor(current/2)] > this.heap[current]) {
/* Swapping the two nodes by using the ES6 destructuring syntax*/
[this.heap[Math.floor(current/2)], this.heap[current]] = [this.heap[current], this.heap[Math.floor(current/2)]]
current = Math.floor(current/2)
}
}
}
remove() {
/* Smallest element is at the index 1 in the heap array */
let smallest = this.heap[1]
/* When there are more than two elements in the array, we put the right most element at the first position
and start comparing nodes with the child nodes
*/
if (this.heap.length > 2) {
this.heap[1] = this.heap[this.heap.length-1]
this.heap.splice(this.heap.length - 1)
if (this.heap.length === 3) {
if (this.heap[1] > this.heap[2]) {
[this.heap[1], this.heap[2]] = [this.heap[2], this.heap[1]]
}
return smallest
}
let current = 1
let leftChildIndex = current * 2
let rightChildIndex = current * 2 + 1
while (this.heap[leftChildIndex] &&
this.heap[rightChildIndex] &&
(this.heap[current] > this.heap[leftChildIndex] ||
this.heap[current] > this.heap[rightChildIndex])) {
if (this.heap[leftChildIndex] < this.heap[rightChildIndex]) {
[this.heap[current], this.heap[leftChildIndex]] = [this.heap[leftChildIndex], this.heap[current]]
current = leftChildIndex
} else {
[this.heap[current], this.heap[rightChildIndex]] = [this.heap[rightChildIndex], this.heap[current]]
current = rightChildIndex
}
leftChildIndex = current * 2
rightChildIndex = current * 2 + 1
}
}
/* If there are only two elements in the array, we directly splice out the first element */
else if (this.heap.length === 2) {
this.heap.splice(1, 1)
} else {
return null
}
return smallest
}
}
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