[Swift]LeetCode703. 数据流中的第K大元素 | Kth Largest Element in a Stream

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Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Your KthLargest class will have a constructor which accepts an integer k and an integer array nums, which contains initial elements from the stream. For each call to the method KthLargest.add, return the element representing the kth largest element in the stream.

Example:

int k = 3;
int[] arr = [4,5,8,2];
KthLargest kthLargest = new KthLargest(3, arr);
kthLargest.add(3);   // returns 4
kthLargest.add(5);   // returns 5
kthLargest.add(10);  // returns 5
kthLargest.add(9);   // returns 8
kthLargest.add(4);   // returns 8

Note:
You may assume that nums' length ≥ k-1 and k ≥ 1.

设计一个找到数据流中第K大元素的类（class）。注意是排序后的第K大元素，不是第K个不同的元素。

你的 KthLargest 类需要一个同时接收整数 k 和整数数组nums 的构造器，它包含数据流中的初始元素。每次调用 KthLargest.add，返回当前数据流中第K大的元素。

示例:

int k = 3;
int[] arr = [4,5,8,2];
KthLargest kthLargest = new KthLargest(3, arr);
kthLargest.add(3);   // returns 4
kthLargest.add(5);   // returns 5
kthLargest.add(10);  // returns 5
kthLargest.add(9);   // returns 8
kthLargest.add(4);   // returns 8

说明:
你可以假设 nums 的长度≥ k-1 且k ≥ 1。

188ms

 1 class KthLargest {
 2     var queue: PriorityQueue
 3     var k: Int
 4     
 5     init(_ k: Int, _ nums: [Int]) {
 6         self.queue = PriorityQueue()
 7         self.k = k
 8         
 9         for val in nums {
10             self.queue.enqueue(val)
11         }
12         
13         var temp = nums.count - k
14         while temp > 0 {
15             self.queue.dequeue()
16             temp -= 1
17         }
18     }
19     
20     func add(_ val: Int) -> Int {
21         queue.enqueue(val)
22         if queue.array.count > k {
23             queue.dequeue()
24         }
25         return queue.peek()!
26     }
27 }
28 
29 struct PriorityQueue {
30     var array = [Int]()
31     
32     func peek() -> Int? {
33         return array.first
34     }
35     
36     mutating func enqueue(_ num: Int) {
37         array.append(num)
38         siftUp()
39     }
40     
41     mutating func dequeue() {
42         array.swapAt(0, array.count - 1)
43         array.removeLast()
44         siftDown()
45     }
46     
47     mutating func siftDown() {
48         var pIndex = 0
49         var sLIndex = 0
50         var sRIndex = 0
51         var index = 0
52         
53         while pIndex * 2 + 1 <= array.count - 1  {
54             sLIndex = pIndex * 2 + 1
55             sRIndex = pIndex * 2 + 2
56             index = pIndex
57             
58             if array[pIndex] > array[sLIndex] {
59                 index = sLIndex
60             }
61             
62             if sRIndex <= array.count - 1 && array[index] > array[sRIndex] {
63                 index = sRIndex
64             }
65             
66             if (pIndex != index) {
67                 array.swapAt(pIndex, index)
68                 pIndex = index
69             } else {
70                 return
71             }
72         }
73     }
74     
75     mutating func siftUp() {
76         var pIndex = 0
77         var sIndex = array.count - 1
78         
79         while sIndex != 0 {
80             pIndex = (sIndex - 1) / 2
81             if (array[sIndex] < array[pIndex]) {
82                 array.swapAt(sIndex, pIndex)
83                 sIndex = pIndex
84             } else {
85                 return
86             }
87         }
88     }
89 }

204ms

  1 class KthLargest {
  2 
  3     let k:Int
  4     let heap = MinHeap()
  5     
  6     init(_ k: Int, _ nums: [Int]) {
  7         self.k = k
  8         for n in nums{
  9             self.heap.add(n)
 10             if self.heap.count > k{
 11                 _ = self.heap.poll()
 12             }
 13         }
 14     }
 15     
 16     func add(_ val: Int) -> Int {
 17         if self.heap.count < k{
 18             self.heap.add(val)
 19             return self.heap.peek()!
 20         }
 21         if val <= self.heap.peek()!{
 22             return self.heap.peek()!
 23         }
 24         _ = self.heap.poll()
 25         self.heap.add(val)
 26         return self.heap.peek()!
 27     }
 28 }
 29 
 30 class MinHeap{
 31     
 32     var data:[Int] = [Int]()
 33     
 34     func parentIndex(_ index:Int) -> Int{
 35         return (index - 1) / 2
 36     }
 37     
 38     func leftChildIndex(_ index:Int) -> Int{
 39         return index * 2 + 1
 40     }
 41     
 42     func rightChildIndex(_ index:Int) -> Int{
 43         return index * 2 + 2
 44     }
 45     
 46     func parent(_ index:Int) -> Int{
 47         return self.data[self.parentIndex(index)]
 48     }
 49     
 50     func leftChild(_ index:Int) -> Int{
 51         return self.data[self.leftChildIndex(index)]
 52     }
 53     
 54     func rightChild(_ index:Int) -> Int{
 55         return self.data[self.rightChildIndex(index)]
 56     }
 57     
 58     func hasParent(_ index:Int) -> Bool{
 59         return self.parentIndex(index) >= 0
 60     }
 61     
 62     func hasLeftChild(_ index:Int) -> Bool{
 63         return self.leftChildIndex(index) < self.data.count
 64     }
 65     
 66     func hasRightChild(_ index:Int) -> Bool{
 67         return self.rightChildIndex(index) < self.data.count
 68     }
 69     
 70     func peek() -> Int?{
 71         return self.data.first
 72     }
 73     
 74     func poll() -> Int{
 75         let first = self.data[0]
 76         self.data[0] = self.data[self.data.count - 1]
 77         self.data.removeLast()
 78         if self.data.count > 1{
 79             self.heapifyDown()
 80         }
 81         return first
 82     }
 83     
 84     func add(_ item:Int){
 85         self.data.append(item)
 86         if self.data.count > 1{
 87             self.heapifyUp()
 88         }
 89     }
 90     
 91     func heapifyUp(){
 92         var currentIndex = self.data.count - 1
 93         while self.hasParent(currentIndex) && self.parent(currentIndex) > self.data[currentIndex]{
 94             self.data.swapAt(currentIndex, self.parentIndex(currentIndex))
 95             currentIndex = self.parentIndex(currentIndex)
 96         }
 97     }
 98     
 99     func heapifyDown(){
100         var currentIndex = 0
101         while self.hasLeftChild(currentIndex){
102             var smallerChildIndex = self.leftChildIndex(currentIndex)
103             if self.hasRightChild(currentIndex) 
104                 && self.rightChild(currentIndex) < self.leftChild(currentIndex){
105                 smallerChildIndex = self.rightChildIndex(currentIndex)
106             }
107             if self.data[currentIndex] > self.data[smallerChildIndex]{
108                 self.data.swapAt(currentIndex, smallerChildIndex)
109                 currentIndex = smallerChildIndex
110             }else{
111                 break
112             }
113         }
114     }
115     
116     var count:Int{
117         return self.data.count
118     }
119 }

Runtime: 208 ms

Memory Usage: 20.1 MB

  1 class KthLargest {
  2     var q: Heap
  3     var k:Int = 0
  4 
  5     init(_ k: Int, _ nums: [Int]) {
  6         self.k = k
  7         q = Heap(sort: <)   
  8         for n in nums
  9         {
 10             add(n)
 11         } 
 12     }
 13     
 14     func add(_ val: Int) -> Int {
 15         if q.count < k
 16         {
 17             q.push(val)
 18         }
 19         else if (q.peek() != nil && q.peek()! < val)
 20         {
 21             q.pop()
 22             q.push(val)            
 23         }
 24         return q.peek()!
 25     }
 26 }
 27 
 28 public struct Heap {    
 29     var elements: [Int] = []
 30     let sort: (Int, Int) -> Bool
 31     var isEmpty: Bool {
 32         return self.elements.isEmpty
 33     }
 34     
 35     var count: Int {
 36         return self.elements.count
 37     }
 38     
 39     func peek() -> Int? {
 40         return elements.first
 41     }
 42     
 43     init(sort: @escaping (Int, Int) -> Bool, elements: [Int] = []) {
 44         self.sort = sort
 45         self.elements = elements
 46         
 47         if !elements.isEmpty {
 48             for i in stride(from: elements.count/2 - 1, through: 0, by: -1) {
 49                 siftDown(from: i)
 50             }
 51         }
 52     }
 53     
 54     mutating func siftDown(from index: Int) {
 55         var parent = index
 56         while true {
 57             let left = leftIndex(of: parent)
 58             let right = rightIndex(of: parent)
 59             var candidate = parent
 60             if left < count && sort(elements[left], elements[candidate]) {
 61                 candidate = left
 62             }
 63             if right < count && sort(elements[right], elements[candidate]) {
 64                 candidate = right
 65             }
 66             if candidate == parent {
 67                 return
 68             }
 69             elements.swapAt(parent, candidate)
 70             parent = candidate
 71         }
 72     }
 73     
 74     mutating func siftUp(from index: Int) {
 75         var child = index
 76         var parent = parentIndex(of: child)
 77         while child > 0 && sort(elements[child], elements[parent]) {
 78             elements.swapAt(child, parent)
 79             child = parent
 80             parent = parentIndex(of: child)
 81         }
 82     }
 83     
 84     mutating func push(_ element: Int) {
 85         elements.append(element)
 86         siftUp(from: count-1)
 87     }
 88     
 89     mutating func pop() -> Int? {
 90         guard !isEmpty else { return nil }
 91         elements.swapAt(0, count-1)
 92         defer {
 93             siftDown(from: 0)
 94         }
 95         return elements.popLast()
 96     }
 97     
 98     func leftIndex(of index: Int) -> Int {
 99         return (2 * index) + 1
100     }
101     
102     func rightIndex(of index: Int) -> Int {
103         return (2 * index) + 2
104     }
105     
106     func parentIndex(of index: Int) -> Int {
107         return (index - 1) / 2
108     }
109 }

224ms

  1 class KthLargest {
  2     let minHeap: Heap<Int>
  3     let k: Int
  4     
  5     init(_ k: Int, _ nums: [Int]) {
  6         minHeap = Heap(elements: nums)    
  7         self.k = k
  8         
  9         while minHeap.count > k {
 10             minHeap.extract()
 11         }
 12     }
 13     
 14     func add(_ val: Int) -> Int {
 15         if minHeap.count < k || val > minHeap.peek()! {
 16             minHeap.insert(val)
 17         }
 18         
 19         if minHeap.count > k {
 20             minHeap.extract()
 21         }
 22         return minHeap.peek()!
 23     }
 24 }
 25 
 26 
 27 public class Heap<T: Comparable> {
 28     private var elements: [T] = []
 29     private let areInIncreasingOrder: (T, T) -> Bool
 30 
 31     public var count: Int {
 32         return elements.count
 33     }
 34 
 35     public var isEmpty: Bool {
 36         return elements.isEmpty
 37     }
 38 
 39     public init(elements: [T] = [], compareWith: @escaping ((T, T) -> Bool) = { $0 < $1 }) {
 40         self.elements = elements
 41         self.areInIncreasingOrder = compareWith
 42 
 43         let firstLeafIndex = elements.count / 2
 44         let lastParentIndex = firstLeafIndex - 1
 45         // Only need to bubble down non-leaf nodes (lastParentIndex to 0)
 46         for i in stride(from: lastParentIndex, through: 0, by: -1) {
 47             siftDown(from: i)
 48         }
 49     }
 50 
 51     public func insert(_ value: T) {
 52         elements.append(value)
 53         siftUp(from: elements.count - 1)
 54     }
 55 
 56     public func peek() -> T? {
 57         return elements.first
 58     }
 59 
 60     public func extract() -> T? {
 61         guard !elements.isEmpty else { return nil }
 62         let max = elements.first!
 63         elements.swapAt(0, elements.count - 1)
 64         elements.removeLast()
 65         siftDown(from: 0)
 66         return max
 67     }
 68 
 69     public func contains(_ element: T) -> Bool {
 70         return firstIndex(of: element, startingAt: 0) != nil
 71     }
 72 
 73     public func remove(_ element: T) -> T? {
 74         guard let indexOfElement = firstIndex(of: element) else { return nil }
 75 
 76         let lastIndex = elements.count - 1
 77         if indexOfElement == lastIndex {
 78             return elements.removeLast()
 79         } else {
 80             elements.swapAt(indexOfElement, lastIndex)
 81             let element = elements.removeLast()
 82 
 83             // May need to either move up or down
 84             siftUp(from: indexOfElement)
 85             siftDown(from: indexOfElement)
 86 
 87             return element
 88         }
 89     }
 90 
 91     // MARK: - Privates
 92 
 93     private func leftChildIndex(for parentIndex: Int) -> Int {
 94         return (2 * parentIndex) + 1
 95     }
 96 
 97     private func rightChildIndex(for parentIndex: Int) -> Int {
 98         return (2 * parentIndex) + 2
 99     }
100 
101     private func parentIndex(for childIndex: Int) -> Int {
102         return (childIndex - 1) / 2
103     }
104 
105     private func firstIndex(of element: T, startingAt startIndex: Int = 0) -> Int? {
106         guard startIndex < count else { return nil }
107 
108         if element == elements[startIndex] {
109             return startIndex
110         } else if element > elements[startIndex] {
111             return nil // can't be in heap
112         } else if let foundIndex = firstIndex(of: element, startingAt: leftChildIndex(for: startIndex)) {
113             return foundIndex // need to check both left and right children
114         } else if let foundIndex = firstIndex(of: element, startingAt: rightChildIndex(for: startIndex)) {
115             return foundIndex // need to check both left and right children
116         }
117 
118         return nil // element was smaller than any element in the heap
119     }
120 
121     private func siftUp(from childIndex: Int) {
122         let child = elements[childIndex]
123         let parentIndex = self.parentIndex(for: childIndex)
124         let parent = elements[parentIndex]
125 
126         if areInIncreasingOrder(child, parent) {
127             elements.swapAt(parentIndex, childIndex)
128             siftUp(from: parentIndex)
129         }
130     }
131 
132     private func siftDown(from parentIndex: Int) {
133         var maxElementIndex = parentIndex
134 
135         let leftChildIndex = self.leftChildIndex(for: parentIndex)
136         if leftChildIndex < elements.count && areInIncreasingOrder(elements[leftChildIndex], elements[maxElementIndex]) {
137             maxElementIndex = leftChildIndex
138         }
139 
140         let rightChildIndex = self.rightChildIndex(for: parentIndex)
141         if rightChildIndex < elements.count && areInIncreasingOrder(elements[rightChildIndex], elements[maxElementIndex]) {
142             maxElementIndex = rightChildIndex
143         }
144 
145         if parentIndex == maxElementIndex {
146             return // base case
147         } else {
148             elements.swapAt(parentIndex, maxElementIndex)
149             siftDown(from: maxElementIndex)
150         }
151     }
152 }

232ms

 1 class KthLargest {
 2     
 3     var nums:[Int]
 4     var k:Int
 5     
 6     init(_ k: Int, _ nums: [Int]) {
 7         self.k = k
 8         self.nums = nums.sorted()
 9     }
10     //[-1, 5]
11     func add(_ val: Int) -> Int {
12         var left = 0
13         var right = nums.count - 1
14         // [2,4,5,8]
15         while left <= right {
16             var mid = (left + right + 1) / 2
17             if nums[mid] == val {
18                 left = mid
19                 right = mid - 1
20             } else if nums[mid] > val {
21                 right = mid - 1
22             } else {
23                 left = mid + 1
24             }
25         }
26         
27         nums.insert(val, at: left)
28         return nums[nums.count - k]
29     }
30 }

244ms

  1 class KthLargest {
  2     
  3     let maxHeap: Heap
  4     let minHeap: Heap
  5     let k: Int
  6     
  7     init(_ k: Int, _ nums: [Int]) {
  8         self.maxHeap = Heap(type: .max, array: nums)
  9         self.minHeap = Heap(type: .min)
 10         self.k = k
 11     }
 12     
 13     func add(_ val: Int) -> Int {
 14         if minHeap.count == k {
 15             if let top = minHeap.peek() {
 16                 if top < val {
 17                     minHeap.insert(val)
 18                     _ = minHeap.pop()
 19                     return minHeap.peek()!
 20                 } else {
 21                     return top
 22                 }
 23             }
 24         } else {
 25             maxHeap.insert(val)
 26             while minHeap.count < k {
 27                 let val = maxHeap.pop()!
 28                 minHeap.insert(val)
 29             }
 30             
 31             return minHeap.peek()!
 32         }
 33         
 34         return 0
 35     }
 36 }
 37 
 38 extension KthLargest {
 39     class Heap {
 40     
 41     // MARK: - HeapType
 42     enum HeapType {
 43         case min
 44         case max
 45         
 46         func compare(_ a: Int, _ b: Int) -> Bool {
 47             switch self {
 48             case .min:
 49                 return a < b
 50             case .max:
 51                 return a > b
 52             }
 53         }
 54     }
 55     
 56     // MARK: - Properties & Init
 57     var heap: [Int]
 58     var type: HeapType
 59     
 60     init(type: HeapType, array: [Int] = []) {
 61         self.type = type
 62         self.heap = array
 63         
 64         guard !array.isEmpty else { return }
 65         
 66         var i = (heap.count - 1) / 2
 67         while i >= 0 {
 68             heapify(i)
 69             i -= 1
 70         }
 71     }
 72     
 73     // MARK: - APIs
 74     
 75     var count: Int {
 76         return heap.count
 77     }
 78     
 79     // O[1]
 80     func pop() -> Int? {
 81         guard let first = heap.first else {
 82             return nil
 83         }
 84         
 85         if let last = heap.last {
 86             heap[0] = last
 87             heapify(0)
 88         }
 89         
 90         heap.removeLast()
 91         
 92         return first
 93     }
 94     
 95     // O[1]
 96     func peek() -> Int? {
 97         return heap.first
 98     }
 99     
100     // O[log(n)]
101     func insert(_ val: Int) {
102         heap.append(val)
103         siftUp(heap.count - 1)
104     }
105     
106     // MARK: - Utilty Methods
107     private func heapify(_ i: Int) {
108         var top = i
109         
110         if let left = left(i), type.compare(heap[left], heap[top]) {
111             top = left
112         }
113         
114         if let right = right(i), type.compare(heap[right], heap[top]) {
115             top = right
116         }
117         
118         if top != i {
119             heap.swapAt(i, top)
120             heapify(top)
121         }
122     }
123     
124     private func siftUp(_ i: Int) {
125         var parent = parentIndex(i)
126         var this = i
127         
128         while let p = parent, type.compare(heap[this], heap[p]) {
129             heap.swapAt(p, this)
130             parent = parentIndex(p)
131             this = p
132         }
133     }
134     
135     private func parentIndex(_ i: Int) -> Int? {
136         guard i > 0 else { return nil }
137         return (i - 1) / 2
138     }
139     
140     private func left(_ i: Int) -> Int? {
141         let left = i * 2 + 1
142         return left < heap.count ? left : nil
143     }
144     
145     private func right(_ i: Int) -> Int? {
146         let right = i * 2 + 2
147         return right < heap.count ? right : nil
148     }
149   }
150 }

252ms

  1 class KthLargest {
  2     
  3     var minHeap: Heap<Int>
  4     var K: Int
  5     init(_ k: Int, _ nums: [Int]) {
  6         minHeap = Heap<Int>(sort: <, elements: nums)
  7         while minHeap.count > k {
  8             minHeap.remove()
  9         }
 10         K = k
 11     }
 12     
 13     func add(_ val: Int) -> Int {
 14         if minHeap.count < K {
 15             
 16             minHeap.insert(val) 
 17         } else if minHeap.peek()! < val {
 18             minHeap.remove()
 19             minHeap.insert(val)
 20         }
 21         return minHeap.peek()!
 22     }
 23 }
 24 
 25 
 26 /**
 27  * Your KthLargest object will be instantiated and called as such:
 28  * let obj = KthLargest(k, nums)
 29  * let ret_1: Int = obj.add(val)
 30  */
 31  
 32 struct Heap<Element: Equatable> {
 33     var elements: [Element] = []
 34     let sort: (Element, Element) -> Bool
 35     init(sort: @escaping (Element, Element) -> Bool,
 36          elements: [Element] = []) {   // ?? Escaping?? Why
 37         self.sort = sort
 38         self.elements = elements
 39         
 40         if !elements.isEmpty {
 41             for i in stride(from: elements.count / 2 - 1, through: 0, by: -1) {
 42                 siftDown(from: i)
 43             }
 44         }
 45     }
 46     
 47     var isEmpty: Bool {
 48         return elements.isEmpty
 49     }
 50     
 51     var count: Int {
 52         return elements.count
 53     }
 54     
 55     func peek() -> Element? {
 56         return elements.first
 57     }
 58     
 59     func leftChildIndex(ofParentAt index: Int) -> Int {
 60         return (2 * index) + 1
 61     }
 62     
 63     func rightChildIndex(ofParentAt index: Int) -> Int {
 64         return 2 * (index + 1)
 65     }
 66     
 67     func parentIndex(ofChildAt index: Int) -> Int {
 68         return (index - 1) / 2
 69     }
 70     
 71     mutating func siftDown(from index: Int) {
 72         var parent = index
 73         while true {
 74             let left = leftChildIndex(ofParentAt: parent)
 75             let right = rightChildIndex(ofParentAt: parent)
 76             var candidate = parent
 77             if left < count && sort(elements[left], elements[candidate]) {
 78                 candidate = left
 79             }
 80             if right < count && sort(elements[right], elements[candidate]) {
 81                 candidate = right
 82             }
 83             if candidate == parent {
 84                 return
 85             }
 86             elements.swapAt(parent, candidate)
 87             parent = candidate
 88         }
 89     }
 90     
 91     mutating func siftUp(from index: Int) {
 92         var child = index
 93         var parent = parentIndex(ofChildAt: child)
 94         while child > 0 && sort(elements[child], elements[parent]) {
 95             elements.swapAt(child, parent)
 96             child = parent
 97             parent = parentIndex(ofChildAt: child)
 98         }
 99     }
100     
101     // Remove
102     // Swap -> Sift Down( compare with two children)
103     mutating func remove() -> Element? {
104         guard !isEmpty else {
105             return nil
106         }
107         elements.swapAt(0, count - 1)
108         defer {
109             siftDown(from: 0)
110         }
111         return elements.removeLast()
112     }
113     
114     // Insert
115     // Append -> sift(guolv) up
116     mutating func insert(_ element: Element) {
117         elements.append(element)
118         siftUp(from: elements.count - 1)
119     }
120     
121     func index(of element: Element, startingAt i: Int) -> Int? {
122         if i >= count {
123             return nil
124         }
125         if sort(element, elements[i]) {
126             return nil
127         }
128         if element == elements[i] {
129             return i
130         }
131         if let j = index(of: element, startingAt: leftChildIndex(ofParentAt: i)) {
132             return j
133         }
134         if let j = index(of: element, startingAt: rightChildIndex(ofParentAt: i)) {
135             return j
136         }
137         return nil
138     }
139 }

256ms

  1 class KthLargest {
  2     
  3     let maxHeap: Heap
  4     let minHeap: Heap
  5     let k: Int
  6     
  7     init(_ k: Int, _ nums: [Int]) {
  8         self.maxHeap = Heap(type: .max, array: nums)
  9         self.minHeap = Heap(type: .min)
 10         self.k = k
 11     }
 12     
 13     func add(_ val: Int) -> Int {
 14         if minHeap.count == k {
 15             if let top = minHeap.peek() {
 16                 if top < val {
 17                     minHeap.insert(val)
 18                     _ = minHeap.pop()
 19                     return minHeap.peek()!
 20                 } else {
 21                     return top
 22                 }
 23             }
 24         } else {
 25             maxHeap.insert(val)
 26             while minHeap.count < k {
 27                 let val = maxHeap.pop()!
 28                 minHeap.insert(val)
 29             }
 30             
 31             return minHeap.peek()!
 32         }
 33         
 34         return 0
 35     }
 36 }
 37 
 38 extension KthLargest {
 39     class Heap {
 40     
 41     // MARK: - HeapType
 42     enum HeapType {
 43         case min
 44         case max
 45         
 46         func compare(_ a: Int, _ b: Int) -> Bool {
 47             switch self {
 48             case .min:
 49                 return a < b
 50             case .max:
 51                 return a > b
 52             }
 53         }
 54     }
 55     
 56     // MARK: - Properties & Init
 57     var heap: [Int]
 58     var type: HeapType
 59     
 60     init(type: HeapType, array: [Int] = []) {
 61         self.type = type
 62         self.heap = array
 63         
 64         guard !array.isEmpty else { return }
 65         
 66         var i = (heap.count - 1) / 2
 67         while i >= 0 {
 68             heapify(i)
 69             i -= 1
 70         }
 71     }
 72     
 73     // MARK: - APIs
 74     
 75     var count: Int {
 76         return heap.count
 77     }
 78     
 79     // O[1]
 80     func pop() -> Int? {
 81         guard let first = heap.first else {
 82             return nil
 83         }
 84         
 85         if let last = heap.last {
 86             heap[0] = last
 87             heapify(0)
 88         }
 89         
 90         heap.removeLast()
 91         
 92         return first
 93     }
 94     
 95     // O[1]
 96     func peek() -> Int? {
 97         return heap.first
 98     }
 99     
100     // O[log(n)]
101     func insert(_ val: Int) {
102         heap.append(val)
103         siftUp(heap.count - 1)
104     }
105     
106     // MARK: - Utilty Methods
107     private func heapify(_ i: Int) {
108         var top = i
109         
110         if let left = left(i), type.compare(heap[left], heap[top]) {
111             top = left
112         }
113         
114         if let right = right(i), type.compare(heap[right], heap[top]) {
115             top = right
116         }
117         
118         if top != i {
119             heap.swapAt(i, top)
120             heapify(top)
121         }
122     }
123     
124     private func siftUp(_ i: Int) {
125         var parent = parentIndex(i)
126         var this = i
127         
128         while let p = parent, type.compare(heap[this], heap[p]) {
129             heap.swapAt(p, this)
130             parent = parentIndex(p)
131             this = p
132         }
133     }
134     
135     private func parentIndex(_ i: Int) -> Int? {
136         guard i > 0 else { return nil }
137         return (i - 1) / 2
138     }
139     
140     private func left(_ i: Int) -> Int? {
141         let left = i * 2 + 1
142         return left < heap.count ? left : nil
143     }
144     
145     private func right(_ i: Int) -> Int? {
146         let right = i * 2 + 2
147         return right < heap.count ? right : nil
148     }
149  }
150 }

344ms

  1 class KthLargest {
  2     private let k: Int
  3     private var count: Int
  4     private var minHeap: MinHeap<Int>
  5 
  6     init(_ k: Int, _ nums: [Int]) {
  7         self.k = k
  8         self.count = 0
  9         self.minHeap = MinHeap<Int>()
 10         for num in nums {
 11             add(num)
 12         }
 13     }
 14 
 15     @discardableResult
 16     func add(_ value: Int) -> Int {
 17         count += 1
 18 
 19         if count <= k {
 20             minHeap.insert(value)
 21             return minHeap.min()!
 22         }
 23 
 24         if value >= minHeap.min()! {
 25             minHeap.delete()
 26             minHeap.insert(value)
 27         }
 28 
 29         return minHeap.min()!
 30     }
 31 }
 32 
 33 /**
 34  * Your KthLargest object will be instantiated and called as such:
 35  * let obj = KthLargest(k, nums)
 36  * let ret_1: Int = obj.add(val)
 37  */
 38  
 39 public class Heap<ValueType: Comparable> {
 40 
 41     public private(set) var values: [ValueType]
 42     private let debug: Bool
 43 
 44     public init(debug: Bool = false) {
 45         values = []
 46         self.debug = debug
 47     }
 48 
 49     public var count: Int {
 50         return values.count
 51     }
 52 
 53     public var isEmpty: Bool {
 54         return values.count <= 0
 55     }
 56 
 57     private var rootNodeIndex: Int {
 58         return 0
 59     }
 60 
 61     private var lastNodeIndex: Int {
 62         return values.count - 1
 63     }
 64 
 65     private func log(_ string: String) {
 66         guard debug else {
 67             return
 68         }
 69 
 70         print(string)
 71     }
 72 
 73     func order(parentNodeValue: ValueType, childNodeValue: ValueType) -> Bool {
 74         return parentNodeValue < childNodeValue
 75     }
 76 
 77     private func order(parentNodeIndex: Int, childNodeIndex: Int) -> Bool {
 78         guard childNodeIndex >= rootNodeIndex && childNodeIndex <= lastNodeIndex else {
 79             return true
 80         }
 81 
 82         guard parentNodeIndex >= rootNodeIndex && parentNodeIndex <= lastNodeIndex else {
 83             return true
 84         }
 85 
 86         return order(parentNodeValue: values[parentNodeIndex], childNodeValue: values[childNodeIndex])
 87     }
 88 
 89     // O(log(n)) time
 90     public func insert(_ value: ValueType) {
 91         values.append(value)
 92         siftUp()
 93         log("[insert] value: (value)")
 94     }
 95 
 96     // O(log(n)) time
 97     @discardableResult
 98     public func delete() -> ValueType? {
 99         guard !isEmpty else {
100             return nil
101         }
102 
103         let rootValue = values[rootNodeIndex]
104         swapValuesAt(index1: rootNodeIndex, index2: lastNodeIndex)
105         values.remove(at: lastNodeIndex)
106         siftDown()
107 
108         log("[delete] value: (rootValue)")
109         return rootValue
110     }
111 
112     // Constant time
113     public func rootValue() -> ValueType? {
114         guard !isEmpty else {
115             return nil
116         }
117 
118         return values[rootNodeIndex]
119     }
120 
121     // MARK: Private methods
122 
123     // Sift down the root node to the correct position until the heap properties are satisfied
124     private func siftDown() {
125         guard !isEmpty else {
126             return
127         }
128 
129         var currentNodeIndex = rootNodeIndex
130         while currentNodeIndex <= lastNodeIndex {
131             let leftNodeIndex = left(of: currentNodeIndex)
132             let rightNodeIndex = right(of: currentNodeIndex)
133 
134             if order(parentNodeIndex: currentNodeIndex, childNodeIndex: leftNodeIndex)
135                 && order(parentNodeIndex: currentNodeIndex, childNodeIndex: rightNodeIndex) {
136                     // current node is at the correct position
137                     break
138             } else if order(parentNodeIndex: leftNodeIndex, childNodeIndex: currentNodeIndex)
139                 && order(parentNodeIndex: leftNodeIndex, childNodeIndex: rightNodeIndex) {
140                     // current node has to swapped with the left node
141                     swapValuesAt(index1: currentNodeIndex, index2: leftNodeIndex)
142                     currentNodeIndex = leftNodeIndex
143             } else if order(parentNodeIndex: rightNodeIndex, childNodeIndex: currentNodeIndex)
144                 && order(parentNodeIndex: rightNodeIndex, childNodeIndex: leftNodeIndex) {
145                     // current node has to swapped with the right node
146                     swapValuesAt(index1: currentNodeIndex, index2: rightNodeIndex)
147                     currentNodeIndex = rightNodeIndex
148             } else {
149                     break
150             }
151         }
152     }
153 
154     // Sift up the last node to the correct position until the heap properties are satisfied
155     private func siftUp() {
156         guard !isEmpty else {
157             return
158         }
159 
160         var currentNodeIndex = lastNodeIndex
161         while currentNodeIndex > rootNodeIndex {
162             let parentNodeIndex = parent(of: currentNodeIndex)
163             if order(parentNodeValue: values[parentNodeIndex], childNodeValue: values[currentNodeIndex]) {
164                 break
165             } else {
166                 swapValuesAt(index1: currentNodeIndex, index2: parentNodeIndex)
167                 currentNodeIndex = parentNodeIndex
168             }
169         }
170     }
171 
172     // MARK: Helper methods
173 
174     private func swapValuesAt(index1: Int, index2: Int) {
175         guard !isEmpty && index1 < count && index2 < count else {
176             return
177         }
178 
179         let temp = values[index1]
180         values[index1] = values[index2]
181         values[index2] = temp
182     }
183 
184     private func left(of index: Int) -> Int {
185         return 2 * index + 1
186     }
187 
188     private func right(of index: Int) -> Int {
189         return 2 * index + 2
190     }
191 
192     private func isValid(index: Int) -> Bool {
193         return index >= 0 && index < values.count
194     }
195 
196     private func parent(of index: Int) -> Int {
197         return Int(ceil(Double(index)/2) - 1.0)
198     }
199 
200     public func printValues() {
201         log("Heap: (values)")
202     }
203 
204 }
205 
206 public class MinHeap<ValueType: Comparable>: Heap<ValueType> {
207 
208     public override init(debug: Bool = false) {
209         super.init(debug: debug)
210     }
211 
212     override func order(parentNodeValue: ValueType, childNodeValue: ValueType) -> Bool {
213         return parentNodeValue <= childNodeValue
214     }
215 
216     public func min() -> ValueType? {
217         return rootValue()
218     }
219 }
220 
221 public class MaxHeap<ValueType: Comparable>: Heap<ValueType> {
222 
223     public override init(debug: Bool = false) {
224         super.init(debug: debug)
225     }
226 
227     override func order(parentNodeValue: ValueType, childNodeValue: ValueType) -> Bool {
228         return parentNodeValue >= childNodeValue
229     }
230 
231     public func max() -> ValueType? {
232         return rootValue()
233     }
234 }

1076ms

 1 class KthLargest {
 2     var list:[Int] = [Int]()
 3     var kth:Int = 0
 4     init(_ k: Int, _ nums: [Int]) {
 5         var nums = nums
 6         nums.sort(by: >)
 7         for num in nums {
 8             if list.count <= k {
 9             list.append(num)
10             }
11         }
12         kth = k
13     }
14     
15     func add(_ val: Int) -> Int {
16         if list.count == 0 {
17             list.append(val)
18         } else {
19          if val > list.last! {
20         for i in 0 ..< list.count {
21             var temp = list[i] 
22             if val >= temp {
23               list.insert(val, at: i)
24                 break;
25         }
26      }
27         }else {
28            if list.count < kth {
29           list.append(val)
30        }     
31          }
32       if list.count > kth {
33           list.removeLast()
34        }   
35         }
36       return list[kth-1]
37     } 
38 }

1408ms

 1 class KthLargest {
 2     
 3     fileprivate var array :[Int]
 4     fileprivate var k :Int
 5     
 6     init(_ k: Int, _ nums: [Int]) {
 7         array = nums
 8         self.k = k
 9         
10         if array.count >= k {
11             array.sort(by: >)
12             array = Array(array[0...k-1])
13         }
14         
15     }
16     
17     func add(_ val: Int) -> Int {
18         
19         if array.count < k-1 {
20             
21             array.append(val)
22             return 0
23             
24         }else if array.count == k-1{
25             
26             array.append(val)
27             array = array.sorted(by: >)
28     
29             return array[k-1]
30         }
31         
32         if val >= array[0] {
33             
34             array.insert(val, at: 0)
35             array.removeLast()
36             
37         }else if val < array[k-1] {
38             // 空
39         }else {
40             
41             for i in 0...k-1 {
42                 if array[i] <= val {
43                     array.insert(val, at: i)
44                     array.removeLast()
45                     break
46                 }
47             }
48         }
49         
50         return array[k-1]
51     }
52 }

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原文地址：https://www.cnblogs.com/strengthen/p/10622690.html