题目：

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?

思路：

该题是一道与二进制位运算有关的题目。首先将给定数字n的第一位的数字取出将其向左移动31位。再取第二位数字，向左移动30位，依次类推。

代码：

public int reverseBits(int n) {
        int result = 0;
        for(int i=0;i<32;i++){
            result |= ((n>>i)&1) << (31-i);
        }
        return result;
}