190_ReverseBits.java

// 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?


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