find the kth largest key in a map in swift

To find the kth largest key in a Swift Dictionary (which is essentially a map), one approach is to sort the keys in descending order and then return the kth key.

Here's the code to accomplish this:

main.swift
func findKthLargestKey<K: Comparable, V>(map: [K: V], k: Int) -> K? {
    let sortedKeys = map.keys.sorted(by: >)
    guard k <= sortedKeys.count else { return nil }
    return sortedKeys[k - 1]
}
197 chars
6 lines

In the findKthLargestKey function, we first sort the keys in descending order using the sorted(by:) method with the greater-than (>) operator as the sorting criterion. We then use guard statement to check if the value of k is within the bounds of the array of sorted keys. Finally, we return the kth key by subtracting 1 from k to account for 0-indexing.

Usage example:

main.swift
let scores = ["Alice": 80, "Bob": 70, "Charlie": 90, "David": 75]
let kthKey = findKthLargestKey(map: scores, k: 2)
print(kthKey) // Output: David
147 chars
4 lines

In this example, we pass a dictionary with the keys being the names of students and the values being their corresponding scores. We then call the findKthLargestKey function with a value of 2 for k to get the second largest key (which is "David" in this case).