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Commit df717f7

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feat: add swift implementation to lcof2 problem: No.031 (doocs#3036)
1 parent 532bfa2 commit df717f7

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‎lcof2/剑指 Offer II 031. 最近最少使用缓存/README.md‎

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@@ -667,6 +667,99 @@ public class LRUCache {
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*/
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```
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#### Swift
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```swift
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class Node {
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var key: Int
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var val: Int
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var prev: Node?
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var next: Node?
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init() {
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self.key = 0
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self.val = 0
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}
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init(_ key: Int, _ val: Int) {
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self.key = key
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self.val = val
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}
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}
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class LRUCache {
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private var cache = [Int: Node]()
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private let head: Node
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private let tail: Node
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private let capacity: Int
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private var size: Int
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init(_ capacity: Int) {
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self.capacity = capacity
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self.size = 0
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self.head = Node()
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self.tail = Node()
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head.next = tail
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tail.prev = head
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}
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func get(_ key: Int) -> Int {
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guard let node = cache[key] else {
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return -1
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}
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moveToHead(node)
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return node.val
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}
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func put(_ key: Int, _ value: Int) {
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if let node = cache[key] {
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node.val = value
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moveToHead(node)
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} else {
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let newNode = Node(key, value)
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cache[key] = newNode
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addToHead(newNode)
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size += 1
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if size > capacity {
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let tail = removeTail()
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cache.removeValue(forKey: tail.key)
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size -= 1
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}
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}
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}
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private func moveToHead(_ node: Node) {
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removeNode(node)
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addToHead(node)
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}
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private func removeNode(_ node: Node) {
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node.prev?.next = node.next
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node.next?.prev = node.prev
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}
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private func addToHead(_ node: Node) {
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node.next = head.next
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node.prev = head
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head.next?.prev = node
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head.next = node
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}
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private func removeTail() -> Node {
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let node = tail.prev!
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removeNode(node)
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return node
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}
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}
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/**
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* Your LRUCache object will be instantiated and called as such:
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* let obj = LRUCache(capacity)
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* let ret_1: Int = obj.get(key)
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* obj.put(key, value)
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*/
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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class Node {
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var key: Int
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var val: Int
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var prev: Node?
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var next: Node?
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init() {
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self.key = 0
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self.val = 0
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}
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init(_ key: Int, _ val: Int) {
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self.key = key
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self.val = val
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}
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}
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class LRUCache {
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private var cache = [Int: Node]()
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private let head: Node
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private let tail: Node
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private let capacity: Int
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private var size: Int
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init(_ capacity: Int) {
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self.capacity = capacity
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self.size = 0
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self.head = Node()
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self.tail = Node()
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head.next = tail
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tail.prev = head
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}
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func get(_ key: Int) -> Int {
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guard let node = cache[key] else {
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return -1
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}
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moveToHead(node)
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return node.val
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}
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func put(_ key: Int, _ value: Int) {
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if let node = cache[key] {
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node.val = value
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moveToHead(node)
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} else {
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let newNode = Node(key, value)
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cache[key] = newNode
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addToHead(newNode)
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size += 1
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if size > capacity {
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let tail = removeTail()
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cache.removeValue(forKey: tail.key)
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size -= 1
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}
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}
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}
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private func moveToHead(_ node: Node) {
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removeNode(node)
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addToHead(node)
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}
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private func removeNode(_ node: Node) {
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node.prev?.next = node.next
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node.next?.prev = node.prev
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}
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private func addToHead(_ node: Node) {
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node.next = head.next
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node.prev = head
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head.next?.prev = node
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head.next = node
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}
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private func removeTail() -> Node {
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let node = tail.prev!
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removeNode(node)
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return node
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}
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}
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/**
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* Your LRUCache object will be instantiated and called as such:
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* let obj = LRUCache(capacity)
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* let ret_1: Int = obj.get(key)
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* obj.put(key, value)
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*/

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