输入: n = 10
输出: 12
解释: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 是前 10 个丑数。

/**
 * @param {number} n
 * @return {number}
 */
var nthUglyNumber = function(n) {
   const minHeap=new MinHeap()
   const set=new Set()
   const factors=[2,3,5]
    minHeap.insert(1)
    set.add(1)
    let result;
    for(let i=0;i<n;i++){
        result=minHeap.pop()
        for(const next of factors){
            if(!set.has(next*result)){
                minHeap.insert(next*result)
                set.add(next*result)
            }
        }
    }
    return result
};
 class MinHeap{
    constructor(){
        this.heap=[];
    }
    swap(indexA,indexB){
        let temp=this.heap[indexA]
        this.heap[indexA]=this.heap[indexB]
        this.heap[indexB]=temp
    }
    getParentInex(index){
        return (index-1)>>1;
    }
     getLeftChildIndex(index){
        return index*2+1;
    }
     getRightChildIndex(index){
        return index*2+2;
    }
    shiftUp(index){
        if(index==0){return}
        const parentIndex=this.getParentInex(index)
        //如果当前节点的父节点小于
        if(this.heap[parentIndex]>this.heap[index]){
            this.swap(parentIndex,index)
            this.shiftUp(parentIndex)
        }
    }
    shiftDown(index){
        //获取当前节点的左字节点index，进行下移
        const leftIndex=this.getLeftChildIndex(index)
        if(this.heap[index]>this.heap[leftIndex]){
            this.swap(index,leftIndex)
            this.shiftDown(leftIndex)
        }
        //获取当前节点的右边子节点index，进行下移
        const rightIndex=this.getRightChildIndex(index)
         if(this.heap[index]>this.heap[rightIndex]){
            this.swap(index,rightIndex)
            this.shiftDown(rightIndex)
        }
    }
    insert(value){
        this.heap.push(value);
        this.shiftUp(this.heap.length-1)
    }
    pop(){
        //交换父节点和末尾元素,保证堆的结构不被破坏
        if(this.heap.length===1){  return this.heap.pop();}
        const result=this.heap[0]
        this.heap[0]=this.heap.pop();
        this.shiftDown(0);
        return result
    }
    peek(){
        return this.heap[0];
    }
    size(){
        return this.heap.length;
    }
}