[477]汉明距离总和

参考：
https://leetcode-cn.com/problems/total-hamming-distance/solution/guan-wang-jie-fa-an-wei-zhao-ju-chi-ran-hou-jia-qi/

python思路：补足前面的位数，然后计算每一位0和1的数量且相乘后相加。

class Solution:
    def totalHammingDistance(self, nums) -> int:
        nums_len = len(nums)
        if nums_len == 0:
            return 0
        bin_nums = [bin(num)[2:] for num in nums]
        max_len = max([len(i) for i in bin_nums])
        # 补足数字小的二进制前面部分的0
        bin_nums = ['0' * (max_len - len(i)) + i for i in bin_nums]
        sum = 0
        for i in range(max_len):
            zero_count = [x[i] for x in bin_nums].count('0')
            sum += zero_count * (nums_len - zero_count)
        return sum



if __name__ == '__main__':
    x = Solution()
    print(x[2,14,4])

```

package T477汉明距离总和;

public class Solution {
    public int totalHammingDistance(int[] nums) {
        int[] cnt = new int[32];
        for (int i = 0; i < 32; i++) {
            for (int val : nums) {
                if ((val & (1<<i)) != 0) {
                    cnt[i]++;
                }
            }
        }

        int total = 0;
        for (int i = 0; i < 32; i++) {
            total += (cnt[i]*(nums.length - cnt[i]));
        }

        return total;
    }
}