#147 Easy Time O(1) Space O(1) Animated

Reverse Bits

Reverse the bits of a 32-bit unsigned integer.

Tutor Mode Build the mental model before you memorize the code.

Pattern Bitwise state reduction

Use a bit operation to retain only the information the problem needs while discarding the rest.

Approach: Bit Shifting

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Core Insight

Use a bit operation to retain only the information the problem needs while discarding the rest.

Common Pitfall

Parenthesize shifts and masks, especially when mixing comparison or arithmetic operators.

Description

Reverse the bits of a 32-bit unsigned integer.

TimeO(1) SpaceO(1)

Implementation Plan

Translate the invariant into these small, testable moves.

def reverseBits(n):
    res = 0
    for i in range(32):
        bit = (n >> i) & 1
        res = res | (bit << (31 - i))
    return res