leetcode-349-intersection-of-two-arrays.swift

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https://leetcode.com/problems/intersection-of-two-arrays/


Given two arrays, write a function to compute their intersection.

Example 1:

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]
Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]
Note:

Each element in the result must be unique.
The result can be in any order.

*/

/**
Big O Annotation
Time complexity O(n) where n is the amount of elements in nums2.
Space complexity O(n) where n is the amount of elements in nums1.
*/
func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        
    /**
    Get a set of nums1 for 
    O(1) .contains operation
    */
    var asSet: Set<Int> = Set(nums1)
    var result: Set<Int> = []
    
    // Iterate through nums2
    for element in nums2 {
        
        // Check if num1 contains element
        if asSet.contains(element) {
            result.insert(element)
        }
    }
    
    return Array(result)
}