卖萌的弱渣

I am stupid, I am hungry.

Reverse Bits

Reverse bits of a given 32 bits unsigned integer.

For example, given input 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?

Solution

优化

  • Java:
(Reverse-Bits.java) download
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public class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {
        int result = 0;
        for (int i=0; i<32;i++){
            result += n & 1;
            // n右移1位
            n >>>= 1;
            if (i < 31)
                result <<= 1;
        }
        return result;
    }
}
(Reverse-Bits.py) download
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class Solution(object):
    def reverseBits(self, n):
        """
        :type n: int
        :rtype: int
        """
        ret = 0
        for i in range(32):
            ret <<= 1
            ret |= n & 1
            n >>= 1
        return ret