LeetCode-in-Java
190. Reverse Bits
Easy
Reverse bits of a given 32 bits signed integer.
Example 1:
Input: n = 43261596
Output: 964176192
Explanation:
Integer
Binary
43261596
00000010100101000001111010011100
964176192
00111001011110000010100101000000
Example 2:
Input: n = 2147483644
Output: 1073741822
Explanation:
Integer
Binary
2147483644
01111111111111111111111111111100
1073741822
00111111111111111111111111111110
Constraints:
0 <= n <= 231 - 2nis even.
Follow up: If this function is called many times, how would you optimize it?
Solution
public class Solution {
// you need treat n as an unsigned value
public int reverseBits(int n) {
int ret = 0;
// because there are 32 bits in total
for (int i = 0; i < 32; i++) {
ret = ret << 1;
// If the bit is 1 we OR it with 1, ie add 1
if ((n & 1) > 0) {
ret = ret | 1;
}
n = n >>> 1;
}
return ret;
}
}