[Swift]LeetCode594. 最长和谐子序列 | Longest Harmonious Subsequence

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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.

---

和谐数组是指一个数组里元素的最大值和最小值之间的差异正好是1。

如今，给定一个整数数组，你须要在全部可能的子序列中找到最长的和谐子序列的长度。

示例 1:

输入: [1,3,2,2,5,2,3,7]
输出: 5
缘由: 最长的和谐数组是：[3,2,2,2,3].

说明: 输入的数组长度最大不超过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         //将数组中的值存入字典
 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         //最长和谐子序列
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 }