Function bus_factor 

pub fn bus_factor(
    knowledge_shares_percent: &[f64],
    critical_threshold_percent: f64,
) -> Option<usize>

The bus factor: the minimum number of people whose combined knowledge share meets or exceeds critical_threshold_percent (commonly 50.0).

Sorts a copy of knowledge_shares_percent in descending order and accumulates from the largest share down, counting how many people it takes to reach the threshold. A low result means knowledge is dangerously concentrated in a few people; a high result means it is spread widely.

Arguments

• knowledge_shares_percent — each person’s percentage share of understanding or ownership of the system. Values are assumed to be finite, non-NaN percentages (they need not sum to exactly 100.0).
• critical_threshold_percent — the combined share (e.g. 50.0) whose loss is considered critical.

Returns

The number of people whose combined share reaches the threshold, or None if knowledge_shares_percent is empty, or if the shares never reach critical_threshold_percent even after summing all of them.

Examples

use software_engineering::documentation_and_knowledge_metrics::bus_factor;

// One person alone holds 60%, past the 50% threshold.
assert_eq!(bus_factor(&[60.0, 25.0, 15.0], 50.0), Some(1));

// Five even 20% shares need three of them to cross 50%.
assert_eq!(bus_factor(&[20.0, 20.0, 20.0, 20.0, 20.0], 50.0), Some(3));

assert_eq!(bus_factor(&[], 50.0), None);
// Shares that never reach the threshold even combined.
assert_eq!(bus_factor(&[10.0, 10.0], 50.0), None);