LeetCode 191. Number of 1 Bits

題目

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).

For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.

翻譯

給一個整數，找出這個整數有幾個'1'，例如11用32-bit表示 '00000000000000000000000000001011'，總共有3個1，return 3

思路

這題不考慮效能的話只要收先將將數字n轉為2進位字串，然後跑迴圈找出有多少1。

解題

/**
 * @param {number} n - a positive integer
 * @return {number}
 */
var hammingWeight = function(n) {
    var count = 0  ;

    // n轉為二進位
    var ary = n.toString(2).split("");
    for(var i in ary){
        if(ary[i] % 2 ==1){
            count++;
        }
    }
  return count;      
};