[LeetCode] 190. Reverse Bits_Easy tag: Bit Manipulation

Reverse bits of a given 32 bits unsigned integer.

Example:

Input: 43261596
Output: 964176192
Explanation: 43261596 represented in binary as 00000010100101000001111010011100,
             return 964176192 represented in binary as 00111001011110000010100101000000.

Follow up:
If this function is called many times, how would you optimize it?

这个题目就是利用Bit Manipulation, 依次将每位n的最后一位移到ans的前面, T: O(1)

Code

class Solution:
    def reverseBits(self, n):
        ans = 0
        for _ in range(32):
            ans = (ans<<1) + (n&1)
            n >>= 1
        return ans