JS min hep

min-heap.js

class MinHeap {
    constructor(data = []) {
        this.data = data;
        this.comparator = (a, b) => a - b;
        this.heapify();
    }

    heapify() {
        if (this.size < 2) return;
        for (let i = 1; i < this.size; i++) {
            this.bubbleUp(i);
        }
    }

    peek() {
        if (this.size === 0) return null;
        return this.data[0];
    }

    push(value) {
        this.data.push(value);
        this.bubbleUp(this.size - 1);
    }

    pop() {
        if (this.size === 0) {
            return null;
        }
        const result = this.data[0];
        const last = this.data.pop();
        if (this.size !== 0) {
            this.data[0] = last;
            this.bubbleDown(0);
        }
        return result;
    }

    bubbleUp(index) {
        while (index > 0) {
            const parentIndex = (index - 1) >> 1;
            if (this.comparator(this.data[index], this.data[parentIndex]) < 0) {
                this.swap(index, parentIndex);
                index = parentIndex;
            } else {
                break;
            }
        }
    }

    bubbleDown(index) {
        const lastIndex = this.size - 1;
        while (true) {
            const leftIndex = index * 2 + 1;
            const rightIndex = index * 2 + 2;
            let findIndex = index;
            if (
                leftIndex <= lastIndex &&
                this.comparator(this.data[leftIndex], this.data[findIndex]) < 0
            ) {
                findIndex = leftIndex;
            }
            if (
                rightIndex <= lastIndex &&
                this.comparator(this.data[rightIndex], this.data[findIndex]) < 0
            ) {
                findIndex = rightIndex;
            }
            if (index !== findIndex) {
                this.swap(index, findIndex);
                index = findIndex;
            } else {
                break;
            }
        }
    }

    swap(index1, index2) {
        [this.data[index1], this.data[index2]] = [this.data[index2], this.data[index1]];
    }

   get size() {
        return this.data.length;
    }
}