[Swift]LeetCode621. 任務調度器 | Task Scheduler

時間 2019-11-11

標籤 swift leetcode621 leetcode 任務調度 task scheduler 欄目 Swift 简体版

原文原文鏈接

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Given a char array representing tasks CPU need to do. It contains capital letters A to Z where different letters represent different tasks. Tasks could be done without original order. Each task could be done in one interval. For each interval, CPU could finish one task or just be idle.git

However, there is a non-negative cooling interval n that means between two same tasks, there must be at least n intervals that CPU are doing different tasks or just be idle.github

You need to return the least number of intervals the CPU will take to finish all the given tasks. api

Example:數組

Input: tasks = ["A","A","A","B","B","B"], n = 2
Output: 8
Explanation: A -> B -> idle -> A -> B -> idle -> A -> B.

Note:微信

The number of tasks is in the range [1, 10000].
The integer n is in the range [0, 100].

給定一個用字符數組表示的 CPU 須要執行的任務列表。其中包含使用大寫的 A - Z 字母表示的26 種不一樣種類的任務。任務能夠以任意順序執行，而且每一個任務均可以在 1 個單位時間內執行完。CPU 在任何一個單位時間內均可以執行一個任務，或者在待命狀態。spa

然而，兩個相同種類的任務之間必須有長度爲 n 的冷卻時間，所以至少有連續 n 個單位時間內 CPU 在執行不一樣的任務，或者在待命狀態。rest

你須要計算完成全部任務所須要的最短期。code

示例 1：htm

輸入: tasks = ["A","A","A","B","B","B"], n = 2
輸出: 8
執行順序: A -> B -> (待命) -> A -> B -> (待命) -> A -> B.

注：

任務的總個數爲 [1, 10000]。
n 的取值範圍爲 [0, 100]。

Runtime: 1100 ms

Memory Usage: 20.2 MB

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         var cnt:[Int] = [Int](repeating:0,count:26)
 4         for task in tasks
 5         {
 6             //A:65
 7             cnt[task.ascii - 65] += 1
 8         }
 9         cnt.sort()
10         var i:Int = 25
11         var mx:Int = cnt[25]
12         var len:Int = tasks.count
13         while (i >= 0 && cnt[i] == mx)
14         {
15             i -= 1
16         }
17         return max(len, (mx - 1) * (n + 1) + 25 - i)        
18     }
19 }
20 
21 //Character擴展 
22 extension Character  
23 {  
24   //轉ASCII整數值(定義小寫爲整數值)
25    var ascii: Int {
26        get {
27            return Int(self.unicodeScalars.first!.value)
28        }       
29     }    
30 }

1118ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         guard !tasks.isEmpty else {return 0}
 4         var map = [Int](repeating: 0, count: 26)
 5         let taskStr = String(tasks)
 6         let offset = "A".utf8.first!
 7         for task in taskStr.utf8{
 8             let count = Int(task - offset)
 9             map[count] += 1
10         }
11         var mostFrequency = 0
12         var numOfMostFrequency = 0
13         for count in map {
14             if count == mostFrequency {
15                 numOfMostFrequency += 1
16             } else if count > mostFrequency {
17                 mostFrequency = count
18                 numOfMostFrequency = 1
19             }
20         }
21         
22         return max((n+1) * (mostFrequency-1) + numOfMostFrequency, tasks.count)
23     }
24 }

1208ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         guard n > 0 else { return tasks.count }
 4         
 5         var items = Array<Int>(repeating: 0, count: 26)
 6         let aValue = Int(UnicodeScalar("A").value)
 7         tasks.forEach { (char) in
 8             items[Int(UnicodeScalar(String(char))!.value) - aValue] += 1
 9         }
10         
11         items.sort()
12         var maxCount = items[25] - 1
13         var maxIdleTimes = (items[25] - 1) * n
14         
15         for i in 1..<items.count {
16             guard items[25 - i] > 0 else { continue }
17             maxIdleTimes -= min(maxCount, items[25 - i])
18         }
19         
20         return maxIdleTimes < 0 ? tasks.count : tasks.count + maxIdleTimes
21     }
22 }

1224ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         var counter = [Character: Int]()
 4         tasks.forEach{ counter[$0, default: 0] += 1 }
 5         let m = counter.values.max()!
 6         let numMax = counter.values.filter{ $0 == m }.count
 7         let slots = (m - 1) * (n + 1)
 8         return numMax + max(slots, tasks.count - numMax)
 9     }
10 }

1240ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         var counts = [Character:Int]()
 4         for task in tasks {
 5             counts[task, default: 0] += 1   
 6         }
 7         var keys = counts.keys.sorted {
 8             return counts[$0]! > counts[$1]!
 9         }
10         let maxCount = counts[keys.first!]!
11         keys.removeFirst()
12         var idleSlots = (maxCount - 1) * n
13         for char in keys {
14             idleSlots -= min(maxCount - 1, counts[char]!)
15             idleSlots = max(idleSlots, 0)
16         }
17         return idleSlots + tasks.count
18     }
19 }

1252ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         let totalTask = tasks.count
 4         guard totalTask > 0 else { return 0 }
 5         guard n > 0 else { return totalTask }
 6         var taskCount: [Character: Int] = [:]
 7         var biggestTaskCount = 1
 8         for task in tasks {
 9             if let count = taskCount[task] {
10                 taskCount[task] = count + 1
11                 if biggestTaskCount < count + 1 {
12                     biggestTaskCount = count + 1
13                 }
14             }else {
15                 taskCount[task] = 1
16             }
17         }
18         
19         if (biggestTaskCount * (n + 1)) <= tasks.count {
20             return tasks.count
21         }
22         
23         
24         var total = (biggestTaskCount - 1) * (n + 1)
25         
26         for (_, value) in taskCount {
27             if value == biggestTaskCount {
28                 total += 1
29             }
30         }
31         
32         return total
33     }
34 }

1256ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         var map = [Character: Int]()
 4         var maxCount = 0
 5         for task in tasks {
 6             if let val = map[task] {
 7                 map[task] = val + 1
 8                 maxCount = max(maxCount, val + 1)
 9             } else {
10                 maxCount = max(maxCount, 1)
11                 map[task] = 1
12             }
13         }
14         
15         let sortedMap = map.sorted { $0.1 > $1.1 }
16         maxCount -= 1
17         var idlesAmount = maxCount * n
18         var charCount = maxCount
19         for i in 1..<sortedMap.count {
20             let (key, val)  = sortedMap[i]
21             idlesAmount -= min(val, maxCount)
22         } 
23         
24         return idlesAmount > 0 ? tasks.count + idlesAmount : tasks.count        
25     }
26 }

1260ms

 1 class Solution {
 2     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
 3         var countMap: [Character: Int] = [:]
 4         for task in tasks {
 5             countMap[task] = (countMap[task] ?? 0) + 1
 6         }
 7         let maxCount: Int = countMap.values.max() ?? 0
 8         let fullPeriodCount = maxCount - 1
 9         var maxIdles = fullPeriodCount * (n + 1)
10         for count in countMap.values {
11             maxIdles -= min(fullPeriodCount, count)
12         }
13         return tasks.count + max(0, maxIdles)
14     }
15 }

1264ms

 1 class Solution {
 2     func isValid(_ intervals: Int, _ table: [Character: Int], _ len: Int, _ maxCount: Int, _ maxCountTies: Int) -> Bool {
 3         let rest = intervals%len
 4         var rounds = intervals/len + (rest == 0 ? 0 : 1)
 5         if rounds < maxCount || (rounds == maxCount && 0 < rest && rest < maxCountTies) {
 6             return false
 7         }
 8         
 9         return true
10     }
11     
12     func binarySearch(_ low: Int, _ high: Int, _ table: [Character : Int], _ n: Int, _ maxCount: Int, _ maxCountTies: Int) -> Int {
13         if low == high {
14             return low
15         }
16         
17         let mid = (low+high)/2
18         if isValid(mid, table, n, maxCount, maxCountTies) == true {
19             return binarySearch(low, mid, table, n, maxCount, maxCountTies)
20         } else {
21             return binarySearch(mid+1, high, table, n, maxCount, maxCountTies)
22         }
23         
24     }
25     
26     func leastInterval(_ tasks: [Character], _ n: Int) -> Int {
27         if tasks.count == 0 {
28             return 0
29         }
30         
31         if n == 0 {
32             return tasks.count
33         }
34         
35         var table: [Character: Int] = [:]
36         for ch in tasks {
37             table[ch] = (table[ch] ?? 0) + 1
38         }
39         
40         var maxCount = table.values.reduce(0, {max($0, $1)})
41         var maxCountTies = table.values.reduce(0, {$0 + ($1 == maxCount ? 1 : 0)})
42      
43         let tasksCount = tasks.count
44         let low = max(tasksCount, (maxCount-1)*(n+1)+1)
45         let high = tasksCount*(n+1)
46         
47         return binarySearch(low, high, table, n+1, maxCount, maxCountTies)        
48     }
49 }