Swift - Functions
You want to write a Swift function that accepts a variadic list of integers and returns a dictionary where keys are the integers and values are their squares. Which function correctly implements this?
You want to write a Swift function that accepts a variadic list of integers and returns a dictionary where keys are the integers and values are their squares. Which function correctly implements this?
hard📝 Application Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Understand desired output
We want a dictionary mapping each integer to its square.Step 2: Check each option
func squares(_ nums: Int...) -> [Int: Int] { var dict = [Int: Int]() for n in nums { dict[n] = n * n } return dict } correctly creates a dictionary and assigns squares. func squares(nums: Int...) -> [Int: Int] { return nums.map { ($0, $0 * $0) } } returns an array of tuples, not a dictionary. func squares(_ nums: Int...) -> [Int: Int] { return nums.reduce([:]) { $0 + [$1: $1 * $1] } } uses invalid '+' on dictionaries. func squares(_ nums: Int...) -> [Int: Int] { var dict = [Int: Int]() for n in nums { dict.append(n * n) } return dict } tries to append to a dictionary, which is invalid.Final Answer:
func squares(_ nums: Int...) -> [Int: Int] { var dict = [Int: Int]() for n in nums { dict[n] = n * n } return dict } -> Option DQuick Check:
Use dictionary assignment to build key-value pairs [OK]
Quick Trick: Use dict[key] = value to build dictionary in loop [OK]
Common Mistakes:
- Using map returns array, not dictionary
- Trying to append to dictionary
- Using invalid operators on dictionaries
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