mathball/lib/popcount/index.js

A JavaScript library for Competitive Programming

'use strict';

/* Function: popcount() */

var validate = require('../validation/positive-integer');

function popcount(num) {
  var count = 0;
  while (num) {
    num &= num - 1;
    count++;
  }
  return count;
}

module.exports = function (num) {
  validate(num, 'popcount');
  return popcount(num);
};