[Swift]LeetCode349. 两个数组的交集 | Intersection of Two Arrays

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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.

---

给定两个数组，编写一个函数来计算它们的交集。

示例 1:

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

示例 2:

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

说明:

• 输出结果中的每个元素一定是唯一的。
• 我们可以不考虑输出结果的顺序。

---

12ms

class Solution {
    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        var pool: [Int: Int] = [:]
        for num in nums1 {
            pool[num] = 1
        }
        
        var result: [Int] = []
        for num in nums2 {
            if pool[num] != nil {
                pool[num] = nil
                result.append(num)
            }
        }
        
        return result
    }
}

---

16ms

class Solution {
    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
    if nums1.count == 0 || nums2.count == 0 {
        return [];
    }

    var intersectionDic:[Int:Bool] = Dictionary();

    for number in nums1 {
        intersectionDic[number] = true
    }

    var intersectionArray:[Int] = Array();
    for  number in nums2  {
        let hasIntersection = intersectionDic[number] ?? false
        guard hasIntersection else {continue}

        intersectionArray.append(number)
        intersectionDic[number] = false
    }

    return intersectionArray;
    }
}

class Solution {
    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        //利用Set的基本集合操作
        var set1:Set<Int> = Set(nums1)
        var set2:Set<Int> = Set(nums2)
        var res:Set<Int> = set1.intersection(set2)
        //Set转Array
        return Array(res)
    }
}

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

---

20ms

class Solution {
    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        var sortedNums1 = nums1.sorted()
        var sortedNums2 = nums2.sorted()
        var ret: Set<Int> = []
        var i = 0
        var j = 0
        
        while i < sortedNums1.count && j < sortedNums2.count {
            if sortedNums1[i] > sortedNums2[j] {
                j+=1
            } else if sortedNums1[i] < sortedNums2[j] {
                i+=1
            } else {
                ret.insert(sortedNums1[i])
                i+=1
                j+=1
            }
        }
        
        return Array(ret)
    }
}

---

24ms

class Solution {
    func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
        let s = Set<Int>.init(nums1)
        var result = Set<Int>()
        for value in nums2 {
            if(s.contains(value) && !result.contains(value)){
                result.insert(value)
            }
        }
        return Array<Int>.init(result)
    }
}