DSA TrainerReverse Bits
Reverse the bits of a 32-bit unsigned integer and return the result.
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Problem
Reverse bits of a given 32 bits unsigned integer.
Input
A 32-bit unsigned integer `n`.
Output
The integer formed by reversing the 32 bits of `n`.
Examples
Input: n = 43261596 (00000010100101000001111010011100)
Output: 964176192 (00111001011110000010100101000000)
Input: n = 4294967293 (11111111111111111111111111111101)
Output: 3221225471 (10111111111111111111111111111111)
The brute-force approach
Convert to a binary string, pad to 32 bits, reverse it, convert back to an integer.
bits = bin(n)[2:].zfill(32)
reversed_bits = bits[::-1]
return int(reversed_bits, 2)O(32) = O(1). String conversion is fine but the bit manipulation approach is more direct for interviews.
Spotting the pattern
This is a Bit Manipulation problem. The key question to ask yourself:
If you extract the last bit of n and want to place it in the i-th position of result, which operation shifts it there?
Answering that is where it clicks, and it's exactly what the guided walkthrough below builds with you: the pattern reasoning, a progressive hint ladder that never spoils the answer, a row-by-row dry run, the optimized solution, and an in-browser editor to run your code against real test cases.
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The Bit Manipulation walkthrough for Reverse Bits: the progressive hint ladder, a row-by-row dry run, the optimized code, and an in-browser runner, plus both full courses, DSA and System Design, and every other premium problem.
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