/*

input : 32 bit unsigned integer n

output : unsigned integer representation of reversed bit

constraint :

1) input is always 32 bit unsigned integer

2) implementation should not be affected by programming language

solution 1)

get unsigned integer bit representation

build string s O(n)

reverse O(n)

get integer O(n)

tc : O(n) sc : O(n)

solution 2) one loop

nth bit indicates (1<<n) if reverse (1<< (32 - n))

add up in one loop

return

tc : O(n), sc: O(1)

*/

public class Solution {

// you need treat n as an unsigned value

static final int LENGTH = 32;

public int reverseBits(int n) {

int answer = 0;

for(int i = 0; i < LENGTH; i++) {

if(((1<<i) & n) != 0) {

answer += (1 << (LENGTH - i - 1));

}

}

return answer;

}

}