LeetCode Entry

1009. Complement of Base 10 Integer

11.03.2026 easy 2026 kotlin rust

Invert binary

1009. Complement of Base 10 Integer easy blog post substack youtube

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Problem TLDR

Invert binary #easy

Intuition

Use a bitmask of the next power of two - 1.

Approach

• Kotlin: takeHighestOneBit, countLeadingZeroBits
• Rust: leasing_zeros, next_power_of_two, ilog2

• 0 case trick: use

  1 to check bits count at least 1

Complexity

• Time complexity: \(O(1)\)

• Space complexity: \(O(1)\)

Code

// 0ms
    fun bitwiseComplement(n: Int) =
    (n or 1).takeHighestOneBit()*2 - n - 1

// 0ms
    pub fn bitwise_complement(n: i32) -> i32 {
        n^(2<<(n|1).ilog2())-1
    }