ankitamasand/min-heap-remove.js

## min-heap-remove.js
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 (this.heap[rightChildIndex] === undefined && this.heap[leftChildIndex] < this.heap[current]) {
        [this.heap[current], this.heap[leftChildIndex]] = [this.heap[leftChildIndex], this.heap[current]]
    }

    /* 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
}