Longest harmonious subsequence.

Author: recherst

Easy/594.Longest Harmonious Subsequence.playground/Contents.swift

@@ -0,0 +1,115 @@
+/**
+ We define a harmonious array as an array where the difference between its maximum value and its minimum value is exactly 1.
+
+ Given an integer array nums, return the length of its longest harmonious subsequence among all its possible subsequences.
+
+ A subsequence of array is a sequence that can be derived from the array by deleting some or no elements without changing the order of the remaining elements.
+
+  
+
+ Example 1:
+ Input: nums = [1,3,2,2,5,2,3,7]
+ Output: 5
+ Explanation: The longest harmonious subsequence is [3,2,2,2,3].
+ 
+ Example 2:
+ Input: nums = [1,2,3,4]
+ Output: 2
+ 
+ Example 3:
+ Input: nums = [1,1,1,1]
+ Output: 0
+  
+
+ Constraints:
+ - 1 <= nums.length <= 2 * 10^4
+ - -10^9 <= nums[i] <= 10^9
+ */
+class Solution {
+    func findLHS(_ nums: [Int]) -> Int {
+        if nums.count == 1 { return 0 }
+        let sortedNums = nums.sorted(by: <)
+        print(sortedNums)
+        var result = [Int]()
+        var maxCount = 0
+        var flag = false
+        var i = 0
+        while i < sortedNums.count {
+            if i < sortedNums.count - 1 {
+                if sortedNums[i + 1] - sortedNums[i] == 0 {
+                    result.append(sortedNums[i])
+                } else if sortedNums[i + 1] - sortedNums[i] == 1 {
+                    result.append(sortedNums[i])
+                    flag = true
+                    if result.count > maxCount {
+                        maxCount = result.count
+                    }
+                    if !result.isEmpty {
+                        var newResult = [Int]()
+                        for e in result {
+                            if e >= sortedNums[i] {
+                                newResult.append(e)
+                            }
+                        }
+                        result = newResult
+                    }
+                } else {
+                    if i > 0 {
+                        if sortedNums[i] - sortedNums[i - 1] <= 1 {
+                            result.append(sortedNums[i])
+                        }
+                    }
+                    if flag == true {
+                        if result.count > maxCount {
+                            maxCount = result.count
+                        }
+                    }
+                    result.removeAll()
+                    result.append(sortedNums[i])
+                    flag = false
+                }
+            } else {
+                if sortedNums[i] - sortedNums[i - 1] == 0 {
+                    result.append(sortedNums[i])
+                } else if sortedNums[i] - sortedNums[i - 1] == 1 {
+                    result.append(sortedNums[i])
+                    flag = true
+                    if result.count > maxCount {
+                        maxCount = result.count
+                    }
+                    if !result.isEmpty {
+                        var newResult = [Int]()
+                        for e in result {
+                            if e >= sortedNums[i - 1] {
+                                newResult.append(e)
+                            }
+                        }
+                        result = newResult
+                    }
+                    
+                } else {
+                    if sortedNums[i] - sortedNums[i - 1] <= 1 {
+                        result.append(sortedNums[i])
+                    }
+                    if flag == true {
+                        if result.count > maxCount {
+                            maxCount = result.count
+                        }
+                    }
+                    result.removeAll()
+                    result.append(sortedNums[i])
+                    flag = false
+                }
+            }
+            i += 1
+        }
+        if result.last != result.first && result.count > maxCount {
+            maxCount = result.count
+        }
+        return maxCount
+    }
+}
+
+let s = Solution()
+let r = s.findLHS([1,1,1,1])
+print(r)

Easy/594.Longest Harmonious Subsequence.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/594.Longest Harmonious Subsequence.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -113,6 +113,7 @@
 109. [Array Partition](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/561.Array%20Partition.playground/Contents.swift)
 110. [Reshape the Matrix](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/566.Reshape%20the%20Matrix.playground/Contents.swift)
 111. [Distribute Candies](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/575.Distribute%20Candies.playground/Contents.swift)
+112. [Longest Harmonious Subsequence](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/594.Longest%20Harmonious%20Subsequence.playground/Contents.swift)
 
 #### Medium