SOURCE

function calculateUserList( userIdList ,  costList ,  conversionList ,  avg_cost ) {
    // write code here
    let len = userIdList.length
    function doneList(n,len){
        let k = new Array(len).fill(0)
        let i = 0
        if(n==0)return k
        while(n!=1){
            k[i]=n%2
            n = (n-n%2)/2
            i++
        }
        k[i] = 1
        return k
    }
    let max = 0
    let result = []
    let pp = Math.pow(2,len)
    //let list = doneList(0,len)
    for(let i = 0;i<pp;i++){
        //let i = 0
        let list = doneList(i,len)
        //console.log(list)
        let sum = 0
        let people = 0
        //let sump = 0        
        for(let j = 0;j<len;j++){
            if(list[j]==1){
                sum+=costList[j]
                people+=conversionList[j]
            }
        }
        //console.log(sum)
        //console.log(people)
        if(sum/people<=avg_cost){
            if(people>max){
                max=people
                result = list
            }
        }
    }
    //console.log(result)
    let temp = []
    for(let u = 0;u<len;u++){
        if(result[u]==1){
            temp.push(userIdList[u])
        }
    }
    //console.log(doneList(3,4))
    return temp
}
console.log(calculateUserList([1,2,3,4,5],[2.0, 3.0, 1.0, 4.0, 2.0],[0.2, 0.1, 0.2, 0.1, 0.4],9.5))