Description

Addsrightmost_set_bit function that finds the 1-based position of the rightmost (least significant) set bit in a positive integer.

Algorithm

Usesn & -n to isolate the rightmost set bit, thentrailing_zeros() + 1 for position.

Example: Forn = 18 (binary:10010):

• n & -n = 2 (binary:10)
• trailing_zeros(2) = 1
• position = 1 + 1 = 2 ✓

Features

• ✅$O(1)$ time/space complexity
• ✅ Hardware-optimized (uses BSF/CTZ instruction)
• ✅ Two implementations (trailing_zeros and log2)
• ✅ Comprehensive error handling
• ✅ 15+ test cases

Examples

rightmost_set_bit(18)// Ok(2)  - binary: 10010rightmost_set_bit(12)// Ok(3)  - binary: 1100rightmost_set_bit(5)// Ok(1)  - binary: 101rightmost_set_bit(0)// Err    - no set bits

Testing

All tests pass including:

• Powers of two
• Odd numbers (always position 1)
• Even numbers
• Edge cases (zero, negatives)
• Large numbers
• Both implementations match

Checklist

• Follows Rust style guidelines
• Passes clippy lints
• All tests pass
• Documentation with examples
• Properly exported