82 lines
2.1 KiB
JavaScript
82 lines
2.1 KiB
JavaScript
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class BinaryHeapOpenSet {
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constructor () {
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// Initialing the array heap and adding a dummy element at index 0
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this.heap = [null]
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}
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size () {
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return this.heap.length - 1
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}
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isEmpty () {
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return this.heap.length === 1
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}
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push (val) {
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// Inserting the new node at the end of the heap array
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this.heap.push(val)
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// Finding the correct position for the new node
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let current = this.heap.length - 1
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let parent = current >>> 1
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// Traversing up the parent node until the current node is greater than the parent
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while (current > 1 && this.heap[parent].f > this.heap[current].f) {
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[this.heap[parent], this.heap[current]] = [this.heap[current], this.heap[parent]]
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current = parent
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parent = current >>> 1
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}
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}
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update (val) {
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let current = this.heap.indexOf(val)
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let parent = current >>> 1
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// Traversing up the parent node until the current node is greater than the parent
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while (current > 1 && this.heap[parent].f > this.heap[current].f) {
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[this.heap[parent], this.heap[current]] = [this.heap[current], this.heap[parent]]
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current = parent
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parent = current >>> 1
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}
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}
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pop () {
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// Smallest element is at the index 1 in the heap array
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const smallest = this.heap[1]
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this.heap[1] = this.heap[this.heap.length - 1]
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this.heap.splice(this.heap.length - 1)
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const size = this.heap.length - 1
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if (size < 2) return smallest
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const val = this.heap[1]
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let index = 1
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let smallerChild = 2
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const cost = val.f
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do {
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let smallerChildNode = this.heap[smallerChild]
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if (smallerChild < size - 1) {
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const rightChildNode = this.heap[smallerChild + 1]
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if (smallerChildNode.f > rightChildNode.f) {
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smallerChild++
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smallerChildNode = rightChildNode
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}
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}
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if (cost <= smallerChildNode.f) {
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break
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}
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this.heap[index] = smallerChildNode
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this.heap[smallerChild] = val
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index = smallerChild
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smallerChild *= 2
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} while (smallerChild <= size)
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return smallest
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}
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}
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module.exports = BinaryHeapOpenSet
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