Sorted First / Last

ID

swift.sorted_first_last

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Efficiency

Language

Swift

Tags

collection, efficiency

Description

Reports .sorted().first and .sorted().last. Sorting just to pick the smallest or largest element is O(n log n) for an O(n) answer. Use .min() / .max() (or the by: overloads).

xs.sorted().first              // FLAW — use xs.min()
xs.sorted().last               // FLAW — use xs.max()
xs.sorted(by: <).first         // FLAW — use xs.min(by: <)

xs.min()                       // OK
xs.sorted()                    // OK if you need the whole sequence

Rationale

Sorting an entire sequence to pick a single element wastes work: O(n log n) plus a fresh allocation for an answer that .min() / .max() produce in O(n) with no allocation. On hot paths the difference is easy to measure, and even on cold paths the explicit .min() reads as the intended operation.

Remediation

let smallest = xs.min()
let biggest = xs.max()
let smallestBy = xs.min(by: <)

References