class Node {
    constructor(value, priority) {
        this.value = value;
        this.priority = priority
    }
}

class PriorityQueue{ 
    constructor() {
        this.values = [];
    }
    enqueue(value, priority) {
        let node = new Node(value, priority);
        this.values.push(node);
        this.bubbleUp();
    }
    bubbleUp(){
        let index = this.values.length - 1;
        const element = this.values[index];
        while(index > 0) {
            let parentIndex = floor((index-1)/2);
            let parent = this.values[parentIndex];
            if(element.priority >= parent.priority) break;
            this.values[parentIndex] = element;
            this.values[index] = parent;
            index = parentIndex;
        }
    }
    dequeue() {
        const min = this.values[0];
        const end = this.values.pop();
        if(this.values.length > 0) {
            this.values[0] = end;
            this.bubbleDown();
        }
        return min;
    }
    bubbleDown() {
        let index = 0;
        const length = this.values.length;
        const element = this.value[0];
        while(true) {
            let leftChildIndex = 2 * index + 1; 
            let rightChildIndex = 2 * index + 2; 
            let leftChild;
            let rightChild;
            let swap = null;
            if(leftChildIndex < length) {
                leftChildValue = this.values[leftChildIndex];
                if(leftChild.priority < element.priority) {
                    swap = leftChildIndex
                }
            }
            if(rightChildIndex < length) {
                rightChild = this.values[rightChildIndex];
                if(
                    (swap === null && rightChild.priority < element.priority) || 
                    (swap !== null && rightChild.priority < leftChildValue.priority)
                ){
                    swap = rightChildIndex;
                }
            }
            if(swap === null) break;
            this.values[index] = this.values[swap];
            this.values[swap] = element;
            index = swap;
        }        
    }        
}