Toggle kth Bit

Flip the kth bit of an integer using bitwise XOR.

bit-manipulation xor binary

Write a function `toggle_kth_bit(n: int, k: int) -> int` that takes a non-negative integer `n` and a non-negative integer `k`, and returns the integer obtained by flipping the kth bit of `n` (0-indexed from the least significant bit). The bit is flipped using XOR with a mask that has only that bit set. No bit operations other than XOR and shifts are required.

Examples:
- `toggle_kth_bit(5, 0)` → 4 (5 is 101, flip bit 0 → 100 = 4)
- `toggle_kth_bit(5, 1)` → 7 (5 is 101, flip bit 1 → 111 = 7)
- `toggle_kth_bit(0, 0)` → 1
- `toggle_kth_bit(255, 7)` → 127

Constraints

- `0 <= n <= 10^9`
- `0 <= k <= 30`
- The function must run in O(1) time and O(1) space.

Example

>>> toggle_kth_bit(5, 0)
4
>>> toggle_kth_bit(5, 1)
7
>>> toggle_kth_bit(0, 0)
1
>>> toggle_kth_bit(255, 7)
127

10 points ~10 min

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Hints

Use the XOR operator (^) to flip a single bit.

Create a mask with only the kth bit set using left shift: `1 << k`.

Return `n ^ mask`.

Test Results

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