Reverse digit

Problem

Reverse bits of a given 32 bits unsigned integer.

Example 1

Input: 00000010100101000001111010011100
Output: 00111001011110000010100101000000
Explanation: The input binary string 00000010100101000001111010011100 represents the unsigned integer 43261596, so return 964176192 which its binary representation is 00111001011110000010100101000000. <br>

Example 2

Input: 11111111111111111111111111111101
Output: 10111111111111111111111111111111
Explanation: The input binary string 11111111111111111111111111111101 represents the unsigned integer 4294967293, so return 3221225471 which its binary representation is 10111111111111111111111111111111.

Optimal Solution

Complexity

• Time: O(n)
• Space: O(1)

public int reverseBits(int n) {
    int t = 0;
    for (int i = 0; i < 32; ++i, n >>>= 1) {
        t <<= 1;
        t |= n & 1;
    }
    return t;
}