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?
Related problem: Reverse Integer
Solution
public class Solution {
// you need treat n as an unsigned value
public int reverseBits(int n) {
for (int i = 0; i < 16; i++) {
n = swapBit(n, i, 32-1-i);
}
return n;
}
public int swapBit(int n, int i, int j) {
int a = (n >> i) & 1;
int b = (n >> j) & 1;
if (a != b) {
n ^= 1 << i | 1 << j;
}
return n;
}
}