[Array] Add a solution to Task Scheduler

Author: soapyigu

Array/TaskScheduler.swift

@@ -0,0 +1,29 @@
+/**
+ * Question Link: https://leetcode.com/problems/task-scheduler/
+ * Primary idea: Most frequent character should be put at head of each chunk and join the chunks with less frequent one.
+ *
+ * Time Complexity: O(nlogn), Space Complexity: O(n)
+ *
+ */
+
+ class TaskScheduler {
+    func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
+        guard tasks.count > 0 else {
+            return 0
+        }
+        
+        let taskFreqs = Dictionary(tasks.map { ($0, 1) }, uniquingKeysWith: +)
+        let sortedTasks = taskFreqs.keys.sorted { return taskFreqs[$0]! > taskFreqs[$1]! }
+        var mostFreqCount = 0
+         
+        for sortedTask in sortedTasks {
+            if taskFreqs[sortedTask] != taskFreqs[sortedTasks[0]] {
+                break
+            } 
+            
+            mostFreqCount += 1
+        }
+        
+        return max(tasks.count, (taskFreqs[sortedTasks[0]]! - 1) * (n + 1) + mostFreqCount)
+    }
+}

README.md

@@ -27,7 +27,7 @@
 * [Microsoft](#microsoft)
 
 ## Progress
-[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 231 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
+[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 232 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
 
 
 ## Array
@@ -67,6 +67,7 @@
 [Next Permutation](https://leetcode.com/problems/next-permutation/)| [Swift](./Array/NextPermutation.swift)| Medium| O(n)| O(1)|
 [Gas Station](https://leetcode.com/problems/gas-station/)| [Swift](./Array/GasStation.swift)| Medium| O(n)| O(1)|
 [Game of Life](https://leetcode.com/problems/game-of-life/)| [Swift](./Array/GameLife.swift)| Medium| O(n)| O(1)|
+[Task Scheduler](https://leetcode.com/problems/task-scheduler/)| [Swift](./Array/TaskScheduler.swift)| Medium| O(nlogn)| O(n)|
 [Sliding Window Maximum ](https://leetcode.com/problems/sliding-window-maximum/)| [Swift](./Array/SlidingWindowMaximum.swift)| Hard| O(n)| O(n)|
 [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)| [Swift](./Array/LongestConsecutiveSequence.swift)| Hard| O(n)| O(n)|