[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别正好是1。

现在，给定一个整数数组，你需要在所有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
原因: 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

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
        if nums.count == 0{
            return 0 
        }
        var result = 0
        var map:[Int:Int] = [:]
        for num in nums{
            if let val = map[num]{
                map[num] = val + 1
            }else{
                map[num] = 1
            }
        }
        for (index,num) in map {
            if let value = map[index + 1] {
                result = max(result, map[index]! + map[index + 1]!);
            }
        }
        return result
    }
}

---

232ms

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
        var map: [Int: Int] = [:]
        nums.forEach { (num) in
            if let count = map[num] {
                map[num] = count + 1
            } else {
                map[num] = 1
            }
        }

        var result = 0
        map.forEach { (key, value) in
            result = max(result, value + (map[key - 1] ?? -value))
            result = max(result, value + (map[key + 1] ?? -value))
        }

        return result
    }
}

---

256ms

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
    var map = [Int: Int]()
    
    for num in nums {
        if let value = map[num] {
            map[num] = value + 1
        } else {
            map[num] = 1
        }
    }
    
    let sortedKeys = map.keys.sorted()
    var i = 1
    var long = 0
    
    while i < sortedKeys.count {
        let key1 = sortedKeys[i - 1]
        let key2 = sortedKeys[i]
        if abs(key1 - key2) == 1 {
            let len = map[key1]! + map[key2]!
            if len > long {
                long = len
            }
        }
        
        i += 1
    }
    
    return long
}
}

---

552ms

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
    var dic = [Int: Int]() //num: count
    
    nums.forEach {
        dic[$0, default: 0] += 1
    }
    
    var result = 0
    
    for k in dic.keys {
                
        if let l = dic[k], let r = dic[k + 1] {
            result = max(result, (l + r))
        }
        
    }
    
    return result
    }
}

---

576ms

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
        //将数组中的值存入字典
        var map:[Int:Int] = [Int:Int]()
        for i in nums
        {
            if map[i] == nil
            {
                map[i] = 1
            }
            else
            {
                map[i]! += 1
            }
            
        }
        
        //最长和谐子序列
        var maxLen:Int = 0
        for i in map.keys
        {
            var value1:Int = map[i]!
            var value2:Int = Int()
            if map[i+1] != nil
            {
                value2 = map[i + 1]!
                if (value1 + value2) > maxLen
                {
                    maxLen = value1 + value2
                }
            }
        }
        return maxLen
    }
}

---

696ms

class Solution {
    func findLHS(_ nums: [Int]) -> Int {
    var dic = [Int: Int]() //num: count
    
    nums.forEach {
        dic[$0, default: 0] += 1
    }
    
    var result = 0
    
    for k in dic.keys.sorted() {
                
        if let l = dic[k], let r = dic[k + 1] {
            result = max(result, (l + r))
        }
        
    }
    
    return result
    }
}