IOS 算法(基础篇) ----- 两个数组的交集

题目: 给定两个数组，编写一个函数来计算它们的交集。

例子：

输入：nums1 = [1,2,3,4], nums2 = [2,2]
输出：[2]

输入：nums1 = [7,9,8], nums2 = [9,4,9,8,4,5,10]
输出：[9,8]

遍历法

1.先Set方法去重num1, 减少循环, let set1 = Set(nums1)
(Set和Array的区别在于，Set是无序的，且Set中不能存在重复的元素)
2.遍历set1, 如果num2包含 , result就插入

    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        let set1 = Set(nums1)
        var result: [Int] = []
        for i in set1 {
            if nums2.contains(i){
                result.append(i)
            }
        }
        return result
    }

Swift内置交集方法

intersection:

/// Returns a new set with the elements that are common to both this set and
/// the given sequence.
///
/// In the following example, the bothNeighborsAndEmployees set is made up
/// of the elements that are in both the employees and neighbors sets.
/// Elements that are in only one or the other are left out of the result of
/// the intersection.
///
/// let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
/// let neighbors: Set = ["Bethany", "Eric", "Forlani", "Greta"]
/// let bothNeighborsAndEmployees = employees.intersection(neighbors)
/// print(bothNeighborsAndEmployees)
/// // Prints "["Bethany", "Eric"]"

    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        
        return Array(Set(nums1).intersection(Set(nums2)))
        
    }

题目来源：力扣（LeetCode） 感谢力扣爸爸 :)
IOS 算法合集地址