leetcode Day3 complement number 【补码】

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Note:


The given integer is guaranteed to fit within the range of a 32-bit signed integer.
You could assume no leading zero bit in the integer’s binary representation.

Example 1:
 

Input: 5

Output: 2

Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.

Input: 1

Output: 0

Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.

解决方法：

class Solution(object):

    def findComplement(self, num):

        """

        :type num: int

        :rtype: int

        """

        result=[]

        while num!=0:

            remainder=num%2

            num=num/2

            result.append(remainder)

        l=len(result)



        for i in range(l/2):

            temp=result[i]

            result[i]=result[l-i-1]

            result[l-i-1]=temp

        lam=lambda x:abs(x-1)



        for i in range(l):

            result[i]=lam(result[i])



        #print result

        sum=0

        for i in range(l):

            sum=sum+result[l-i-1]*pow(2,i)

        return sum

PS： 上面的方法是第一次开始做的最原始的方法，巨傻无比。 完全就是一个没学过计算机原理或者微机原理的人的代码哈。 连一个数的补码这种计算机第一节课的内容都还给老师了。。
 
附上最简便的一个解法：

class Solution(object):

    def findComplement(self, num):

        i = 1

        while i <= num:

            i = i << 1

        return (i - 1) ^ num

以为其实一个补码就是一个数与另外一个全1的数进行异或处理哈。
鄙视自己！！！