index.js

/**
 * 338. Counting Bits
Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.

Example:
For num = 5 you should return [0,1,1,2,1,2].

Follow up:

It is very easy to come up with a solution with run time O(n*sizeof(integer)). But can you do it in linear time O(n) /possibly in a single pass?
Space complexity should be O(n).
Can you do it like a boss? Do it without using any builtin function like __builtin_popcount in c++ or in any other language.
 * 
 * @param {number} num
 * @return {number[]}
 */
function countBits1(num) {
    let arr =[0];
    for(let i=1;i<=num;i++){
        let count = i.toString(2).match(/1/g).length
        arr.push(count);
    }
    return arr;
};
function countBits2(num){
	let arr =[0];
    for(let i=1;i<=num;i++){
        let count = i.toString(2).match(/1/g).length
        arr.push(count);
    }
    return arr;
}
module.exports = [countBits1,countBits2];