[Swift]LeetCode349. 兩個數組的交集 | Intersection of Two Arrays

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➤微信公衆號：山青詠芝（shanqingyongzhi）
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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.

---

給定兩個數組，編寫一個函數來計算它們的交集。

示例 1:

輸入: nums1 = [1,2,2,1], nums2 = [2,2]
輸出: [2]

示例 2:

輸入: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
輸出: [9,4]

說明:

• 輸出結果中的每一個元素必定是惟一的。
• 咱們能夠不考慮輸出結果的順序。

 

---

12ms

 1 class Solution {
 2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
 3         var pool: [Int: Int] = [:]
 4         for num in nums1 {
 5             pool[num] = 1
 6         }
 7         
 8         var result: [Int] = []
 9         for num in nums2 {
10             if pool[num] != nil {
11                 pool[num] = nil
12                 result.append(num)
13             }
14         }
15         
16         return result
17     }
18 }

---

16ms

 1 class Solution {
 2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
 3     if nums1.count == 0 || nums2.count == 0 {
 4         return [];
 5     }
 6 
 7     var intersectionDic:[Int:Bool] = Dictionary();
 8 
 9     for number in nums1 {
10         intersectionDic[number] = true
11     }
12 
13     var intersectionArray:[Int] = Array();
14     for  number in nums2  {
15         let hasIntersection = intersectionDic[number] ?? false
16         guard hasIntersection else {continue}
17 
18         intersectionArray.append(number)
19         intersectionDic[number] = false
20     }
21 
22     return intersectionArray;
23     }
24 }

 1 class Solution {
 2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
 3         //利用Set的基本集合操做
 4         var set1:Set<Int> = Set(nums1)
 5         var set2:Set<Int> = Set(nums2)
 6         var res:Set<Int> = set1.intersection(set2)
 7         //Set轉Array
 8         return Array(res)
 9     }
10 }

1 class Solution {
2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {        
3         let intersect = Set(nums1).intersection(Set(nums2))
4         return Array(intersect)
5     }
6 }

---

20ms

 1 class Solution {
 2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
 3         var sortedNums1 = nums1.sorted()
 4         var sortedNums2 = nums2.sorted()
 5         var ret: Set<Int> = []
 6         var i = 0
 7         var j = 0
 8         
 9         while i < sortedNums1.count && j < sortedNums2.count {
10             if sortedNums1[i] > sortedNums2[j] {
11                 j+=1
12             } else if sortedNums1[i] < sortedNums2[j] {
13                 i+=1
14             } else {
15                 ret.insert(sortedNums1[i])
16                 i+=1
17                 j+=1
18             }
19         }
20         
21         return Array(ret)
22     }
23 }

---

24ms

 1 class Solution {
 2     func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
 3         let s = Set<Int>.init(nums1)
 4         var result = Set<Int>()
 5         for value in nums2 {
 6             if(s.contains(value) && !result.contains(value)){
 7                 result.insert(value)
 8             }
 9         }
10         return Array<Int>.init(result)
11     }
12 }