# Very simple non-iterate solution

• ``````class Solution:
# @param n, an integer
# @return an integer
def reverseBits(self, n):
n = ((n & 0x55555555) << 1) | ((n & 0xAAAAAAAA) >> 1)
n = ((n & 0x33333333) << 2) | ((n & 0xCCCCCCCC) >> 2)
n = ((n & 0x0F0F0F0F) << 4) | ((n & 0xF0F0F0F0) >> 4)
n = ((n & 0x00FF00FF) << 8) | ((n & 0xFF00FF00) >> 8)
n = ((n & 0x0000FFFF) << 16) | ((n & 0xFFFF0000) >> 16)
return n
``````

Like merge sort, swap two bits, 4 bits, 8 bits, 16 bits and 32 bits, Then it reversed

• what's wrong with this java code?

``````public int reverseBits(int b) {
n = ((n & 0b10101010101010101010101010101010) >> 1) | ((n & 0b01010101010101010101010101010101) << 1);
n = ((n & 0b11001100110011001100110011001100) >> 2) | ((n & 0b00110011001100110011001100110011) << 2);
n = ((n & 0b11110000111100001111000011110000) >> 4) | ((n & 0b00001111000011110000111100001111) << 4);
n = ((n & 0b11111111000000001111111100000000) >> 8) | ((n & 0b00000000111111110000000011111111) << 8);
n = ((n & 0b11111111111111110000000000000000) >> 16)| ((n & 0b00000000000000001111111111111111) << 16);
return n;
}
``````

doesn't work for one edge case

Input: 65536 (00000000000000010000000000000000)

Output: 4294934528 (11111111111111111000000000000000)

Expected: 32768 (00000000000000001000000000000000)

• U need to use ">>>" rather than ">>".

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