Swift dictionary-backed LRU cache struct

import Foundation

struct LRUCache<Key: Hashable, Value> {
    private let capacity: Int
    private var store: [Key: Value] = [:]
    private var order: [Key] = []
    init(capacity: Int) { self.capacity = max(1, capacity) }
    mutating func get(_ key: Key) -> Value? {
        guard let value = store[key] else { return nil }
        order.removeAll { $0 == key }
        order.append(key)
        return value
    }
    mutating func put(_ key: Key, _ value: Value) {
        store[key] = value
        order.removeAll { $0 == key }
        order.append(key)
        if order.count > capacity { store[order.removeFirst()] = nil }
    }
}