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Commit 1cfc3df

Browse files
feat: add swift implementation to lcci problem: No.16.25 (doocs#2769)
1 parent 67f6f2f commit 1cfc3df

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3 files changed

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3 files changed

+234
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‎lcci/16.25.LRU Cache/README.md‎

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

‎lcci/16.25.LRU Cache/README_EN.md‎

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Original file line numberDiff line numberDiff line change
@@ -623,6 +623,85 @@ public class LRUCache {
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*/
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```
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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(_ key: Int = 0, _ val: Int = 0) {
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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 = Node()
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private let tail: Node = Node()
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private var capacity: Int
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private var size: Int = 0
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init(_ capacity: Int) {
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self.capacity = capacity
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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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if let tailNode = removeTail() {
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cache.removeValue(forKey: tailNode.key)
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size -= 1
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}
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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.prev = head
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node.next = head.next
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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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guard let res = tail.prev, res !== head else {
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return nil
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}
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removeNode(res)
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return res
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}
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}
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```
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<!-- tabs:end -->
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<!-- end -->

‎lcci/16.25.LRU Cache/Solution.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(_ key: Int = 0, _ val: Int = 0) {
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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 = Node()
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private let tail: Node = Node()
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private var capacity: Int
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private var size: Int = 0
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init(_ capacity: Int) {
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self.capacity = capacity
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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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if let tailNode = removeTail() {
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cache.removeValue(forKey: tailNode.key)
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size -= 1
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}
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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.prev = head
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node.next = head.next
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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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guard let res = tail.prev, res !== head else {
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return nil
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}
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removeNode(res)
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return res
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}
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}

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