Leetcode 190: Reverse Bits

Code (bitwise operation)

class Solution:
    # @param n, an integer
    # @return an integer
    def reverseBits(self, n):
        res = 0
        for i in xrange(32):
            res = (res << 1) + (n & 1)
            n = n >> 1
         
        return res

 

Idea

Use n & 1 to get the last bit. Use n >> 1 to shift n to right one bit a time. Use res << 1 to accumulate the result.

Reference: https://discuss.leetcode.com/topic/10298/the-concise-c-solution-9ms

 

Code (Pythonic Cheating!)

class Solution:
    # @param n, an integer
    # @return an integer
    def reverseBits(self, n):
        b = '{:032b}'.format(n)
        return int(b[::-1], 2)

 

Reference: https://discuss.leetcode.com/topic/10069/python-ac-with-63ms-3lines