feat: add swift implementation to lcci problem: No.16.25 (doocs#2769)

Author: klever34

lcci/16.25.LRU Cache/README.md

@@ -610,6 +610,85 @@ public class LRUCache {
  */
 ```
 
+```swift
+class Node {
+    var key: Int
+    var val: Int
+    var prev: Node?
+    var next: Node?
+
+    init(_ key: Int = 0, _ val: Int = 0) {
+        self.key = key
+        self.val = val
+    }
+}
+
+class LRUCache {
+    private var cache: [Int: Node] = [:]
+    private let head: Node = Node()
+    private let tail: Node = Node()
+    private var capacity: Int
+    private var size: Int = 0
+
+    init(_ capacity: Int) {
+        self.capacity = capacity
+        head.next = tail
+        tail.prev = head
+    }
+
+    func get(_ key: Int) -> Int {
+        guard let node = cache[key] else {
+            return -1
+        }
+        moveToHead(node)
+        return node.val
+    }
+
+    func put(_ key: Int, _ value: Int) {
+        if let node = cache[key] {
+            node.val = value
+            moveToHead(node)
+        } else {
+            let newNode = Node(key, value)
+            cache[key] = newNode
+            addToHead(newNode)
+            size += 1
+            if size > capacity {
+                if let tailNode = removeTail() {
+                    cache.removeValue(forKey: tailNode.key)
+                    size -= 1
+                }
+            }
+        }
+    }
+
+    private func moveToHead(_ node: Node) {
+        removeNode(node)
+        addToHead(node)
+    }
+
+    private func removeNode(_ node: Node) {
+        node.prev?.next = node.next
+        node.next?.prev = node.prev
+    }
+
+    private func addToHead(_ node: Node) {
+        node.prev = head
+        node.next = head.next
+        head.next?.prev = node
+        head.next = node
+    }
+
+    private func removeTail() -> Node? {
+        guard let res = tail.prev, res !== head else {
+            return nil
+        }
+        removeNode(res)
+        return res
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.25.LRU Cache/README_EN.md

@@ -623,6 +623,85 @@ public class LRUCache {
  */
 ```
 
+```swift
+class Node {
+    var key: Int
+    var val: Int
+    var prev: Node?
+    var next: Node?
+
+    init(_ key: Int = 0, _ val: Int = 0) {
+        self.key = key
+        self.val = val
+    }
+}
+
+class LRUCache {
+    private var cache: [Int: Node] = [:]
+    private let head: Node = Node()
+    private let tail: Node = Node()
+    private var capacity: Int
+    private var size: Int = 0
+
+    init(_ capacity: Int) {
+        self.capacity = capacity
+        head.next = tail
+        tail.prev = head
+    }
+
+    func get(_ key: Int) -> Int {
+        guard let node = cache[key] else {
+            return -1
+        }
+        moveToHead(node)
+        return node.val
+    }
+
+    func put(_ key: Int, _ value: Int) {
+        if let node = cache[key] {
+            node.val = value
+            moveToHead(node)
+        } else {
+            let newNode = Node(key, value)
+            cache[key] = newNode
+            addToHead(newNode)
+            size += 1
+            if size > capacity {
+                if let tailNode = removeTail() {
+                    cache.removeValue(forKey: tailNode.key)
+                    size -= 1
+                }
+            }
+        }
+    }
+
+    private func moveToHead(_ node: Node) {
+        removeNode(node)
+        addToHead(node)
+    }
+
+    private func removeNode(_ node: Node) {
+        node.prev?.next = node.next
+        node.next?.prev = node.prev
+    }
+
+    private func addToHead(_ node: Node) {
+        node.prev = head
+        node.next = head.next
+        head.next?.prev = node
+        head.next = node
+    }
+
+    private func removeTail() -> Node? {
+        guard let res = tail.prev, res !== head else {
+            return nil
+        }
+        removeNode(res)
+        return res
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.25.LRU Cache/Solution.swift

@@ -0,0 +1,76 @@
+class Node {
+    var key: Int
+    var val: Int
+    var prev: Node?
+    var next: Node?
+
+    init(_ key: Int = 0, _ val: Int = 0) {
+        self.key = key
+        self.val = val
+    }
+}
+
+class LRUCache {
+    private var cache: [Int: Node] = [:]
+    private let head: Node = Node()
+    private let tail: Node = Node()
+    private var capacity: Int
+    private var size: Int = 0
+
+    init(_ capacity: Int) {
+        self.capacity = capacity
+        head.next = tail
+        tail.prev = head
+    }
+
+    func get(_ key: Int) -> Int {
+        guard let node = cache[key] else {
+            return -1
+        }
+        moveToHead(node)
+        return node.val
+    }
+
+    func put(_ key: Int, _ value: Int) {
+        if let node = cache[key] {
+            node.val = value
+            moveToHead(node)
+        } else {
+            let newNode = Node(key, value)
+            cache[key] = newNode
+            addToHead(newNode)
+            size += 1
+            if size > capacity {
+                if let tailNode = removeTail() {
+                    cache.removeValue(forKey: tailNode.key)
+                    size -= 1
+                }
+            }
+        }
+    }
+
+    private func moveToHead(_ node: Node) {
+        removeNode(node)
+        addToHead(node)
+    }
+
+    private func removeNode(_ node: Node) {
+        node.prev?.next = node.next
+        node.next?.prev = node.prev
+    }
+
+    private func addToHead(_ node: Node) {
+        node.prev = head
+        node.next = head.next
+        head.next?.prev = node
+        head.next = node
+    }
+
+    private func removeTail() -> Node? {
+        guard let res = tail.prev, res !== head else {
+            return nil
+        }
+        removeNode(res)
+        return res
+    }
+}