counting-bits.js

// 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.
//
//
//
//
//   You should make use of what you have produced already.
//   Divide the numbers in ranges like [2-3], [4-7], [8-15] and so on. And try to generate new range from previous.
//   Or does the odd/even status of the number help you in calculating the number of 1s?
//
//
// Credits:Special thanks to @ syedee  for adding this problem and creating all test cases.


/**
 * @param {number} num
 * @return {number[]}
 */

var calcBit = function (num) {
    return num.toString(2).replace(/0/g, '').length;
};

var countBits = function(num) {
    var res = new Array(num);
    var i = 0;
    while (i <= num) {
        res[i] = calcBit(i);
        i++
    }
    return res;
    
};