[] Reversed bit leetcode

Reversed given 32-bit unsigned binary integer.

 

Example 1:

Input: 00000010100101000001111010011100
 Output: 00111001011110000010100101000000
 explained: input binary string 00000010100101000001111010011100 unsigned integer 43261596 ,
       the flow returns 964,176,192, which is expressed in binary form 00111001011110000010100101000000 .

Example 2:

Input: 11111111111111111111111111111101
 Output: 10111111111111111111111111111111
 explained: input binary string 11111111111111111111111111111101 unsigned integer 4294967293, 
      thus returns its binary representation is 3221225471 10101111110010110010011101101001.

 

prompt:

• Please note that in some languages ​​(such as Java), there is no unsigned integer type. In this case, the input and output will be designated as a signed integer type, and should not affect your implementation, because both the integer is signed or unsigned, its binary representation of the interior is the same.
• In Java, the compiler uses the twos complement notation to represent signed integers. Thus, in the above  example 2  , the input represents a signed integer  -3, outputs a signed integer  -1073741825.

 

Advanced :
If you repeatedly call this function, you will how to optimize your algorithm?

---

public class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {
        int m = 0;
        for(int i=0;i<32;i++) {
            m<<=1;
            m = m |(n&1);
            n>>=1;
        }
        return m;
    }
}