[Swift]LeetCode594. 最長和諧子序列 | Longest Harmonious Subsequence

★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★
➤微信公衆號：山青詠芝（shanqingyongzhi）
➤博客園地址：山青詠芝（https://www.cnblogs.com/strengthen/）
➤GitHub地址：https://github.com/strengthen/LeetCode
➤原文地址：http://www.javashuo.com/article/p-qvaxambm-me.html 
➤若是連接不是山青詠芝的博客園地址，則多是爬取做者的文章。
➤原文已修改更新！強烈建議點擊原文地址閱讀！支持做者！支持原創！
★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★

We define a harmonious array is an array where the difference between its maximum value and its minimum value is exactly 1.

Now, given an integer array, you need to find the length of its longest harmonious subsequence among all its possible subsequences.

Example 1:

Input: [1,3,2,2,5,2,3,7]
Output: 5
Explanation: The longest harmonious subsequence is [3,2,2,2,3].

 Note: The length of the input array will not exceed 20,000.

---

和諧數組是指一個數組裏元素的最大值和最小值之間的差異正好是1。

如今，給定一個整數數組，你須要在全部可能的子序列中找到最長的和諧子序列的長度。

示例 1:

輸入: [1,3,2,2,5,2,3,7]
輸出: 5
緣由: 最長的和諧數組是：[3,2,2,2,3].

說明: 輸入的數組長度最大不超過20,000.

---

156ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3         if nums.count == 0{
 4             return 0 
 5         }
 6         var result = 0
 7         var map:[Int:Int] = [:]
 8         for num in nums{
 9             if let val = map[num]{
10                 map[num] = val + 1
11             }else{
12                 map[num] = 1
13             }
14         }
15         for (index,num) in map {
16             if let value = map[index + 1] {
17                 result = max(result, map[index]! + map[index + 1]!);
18             }
19         }
20         return result
21     }
22 }

---

232ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3         var map: [Int: Int] = [:]
 4         nums.forEach { (num) in
 5             if let count = map[num] {
 6                 map[num] = count + 1
 7             } else {
 8                 map[num] = 1
 9             }
10         }
11 
12         var result = 0
13         map.forEach { (key, value) in
14             result = max(result, value + (map[key - 1] ?? -value))
15             result = max(result, value + (map[key + 1] ?? -value))
16         }
17 
18         return result
19     }
20 }

---

256ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3     var map = [Int: Int]()
 4     
 5     for num in nums {
 6         if let value = map[num] {
 7             map[num] = value + 1
 8         } else {
 9             map[num] = 1
10         }
11     }
12     
13     let sortedKeys = map.keys.sorted()
14     var i = 1
15     var long = 0
16     
17     while i < sortedKeys.count {
18         let key1 = sortedKeys[i - 1]
19         let key2 = sortedKeys[i]
20         if abs(key1 - key2) == 1 {
21             let len = map[key1]! + map[key2]!
22             if len > long {
23                 long = len
24             }
25         }
26         
27         i += 1
28     }
29     
30     return long
31 }
32 }

---

552ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3     var dic = [Int: Int]() //num: count
 4     
 5     nums.forEach {
 6         dic[$0, default: 0] += 1
 7     }
 8     
 9     var result = 0
10     
11     for k in dic.keys {
12                 
13         if let l = dic[k], let r = dic[k + 1] {
14             result = max(result, (l + r))
15         }
16         
17     }
18     
19     return result
20     }
21 }

---

576ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3         //將數組中的值存入字典
 4         var map:[Int:Int] = [Int:Int]()
 5         for i in nums
 6         {
 7             if map[i] == nil
 8             {
 9                 map[i] = 1
10             }
11             else
12             {
13                 map[i]! += 1
14             }
15             
16         }
17         
18         //最長和諧子序列
19         var maxLen:Int = 0
20         for i in map.keys
21         {
22             var value1:Int = map[i]!
23             var value2:Int = Int()
24             if map[i+1] != nil
25             {
26                 value2 = map[i + 1]!
27                 if (value1 + value2) > maxLen
28                 {
29                     maxLen = value1 + value2
30                 }
31             }
32         }
33         return maxLen
34     }
35 }

---

696ms

 1 class Solution {
 2     func findLHS(_ nums: [Int]) -> Int {
 3     var dic = [Int: Int]() //num: count
 4     
 5     nums.forEach {
 6         dic[$0, default: 0] += 1
 7     }
 8     
 9     var result = 0
10     
11     for k in dic.keys.sorted() {
12                 
13         if let l = dic[k], let r = dic[k + 1] {
14             result = max(result, (l + r))
15         }
16         
17     }
18     
19     return result
20     }
21 }