feat: add Swift codes for linked_list article

codes/swift/Package.swift

@@ -10,6 +10,7 @@ let package = Package(
         .executable(name: "space_complexity", targets: ["space_complexity"]),
         .executable(name: "leetcode_two_sum", targets: ["leetcode_two_sum"]),
         .executable(name: "array", targets: ["array"]),
+        .executable(name: "linked_list", targets: ["linked_list"]),
     ],
     targets: [
         .target(name: "utils", path: "utils"),
@@ -18,5 +19,6 @@ let package = Package(
         .executableTarget(name: "space_complexity", dependencies: ["utils"], path: "chapter_computational_complexity", sources: ["space_complexity.swift"]),
         .executableTarget(name: "leetcode_two_sum", path: "chapter_computational_complexity", sources: ["leetcode_two_sum.swift"]),
         .executableTarget(name: "array", path: "chapter_array_and_linkedlist", sources: ["array.swift"]),
+        .executableTarget(name: "linked_list", dependencies: ["utils"], path: "chapter_array_and_linkedlist", sources: ["linked_list.swift"]),
     ]
 )

codes/swift/chapter_array_and_linkedlist/linked_list.swift

@@ -0,0 +1,91 @@
+/**
+ * File: linked_list.swift
+ * Created Time: 2023-01-08
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import utils
+
+/* 在链表的结点 n0 之后插入结点 P */
+func insert(n0: ListNode, P: ListNode) {
+    let n1 = n0.next
+    n0.next = P
+    P.next = n1
+}
+
+/* 删除链表的结点 n0 之后的首个结点 */
+func remove(n0: ListNode) {
+    if n0.next == nil {
+        return
+    }
+    // n0 -> P -> n1
+    let P = n0.next
+    let n1 = P?.next
+    n0.next = n1
+    P?.next = nil
+}
+
+/* 访问链表中索引为 index 的结点 */
+func access(head: ListNode, index: Int) -> ListNode? {
+    var head: ListNode? = head
+    for _ in 0 ..< index {
+        head = head?.next
+        if head == nil {
+            return nil
+        }
+    }
+    return head
+}
+
+/* 在链表中查找值为 target 的首个结点 */
+func find(head: ListNode, target: Int) -> Int {
+    var head: ListNode? = head
+    var index = 0
+    while head != nil {
+        if head?.val == target {
+            return index
+        }
+        head = head?.next
+        index += 1
+    }
+    return -1
+}
+
+@main
+enum LinkedList {
+    /* Driver Code */
+    static func main() {
+        /* 初始化链表 */
+        // 初始化各个结点
+        let n0 = ListNode(x: 1)
+        let n1 = ListNode(x: 3)
+        let n2 = ListNode(x: 2)
+        let n3 = ListNode(x: 5)
+        let n4 = ListNode(x: 4)
+        // 构建引用指向
+        n0.next = n1
+        n1.next = n2
+        n2.next = n3
+        n3.next = n4
+        print("初始化的链表为")
+        PrintUtil.printLinkedList(head: n0)
+
+        /* 插入结点 */
+        insert(n0: n0, P: ListNode(x: 0))
+        print("插入结点后的链表为")
+        PrintUtil.printLinkedList(head: n0)
+
+        /* 删除结点 */
+        remove(n0: n0)
+        print("删除结点后的链表为")
+        PrintUtil.printLinkedList(head: n0)
+
+        /* 访问结点 */
+        let node = access(head: n0, index: 3)
+        print("链表中索引 3 处的结点的值 = \(node!.val)")
+
+        /* 查找结点 */
+        let index = find(head: n0, target: 2)
+        print("链表中值为 2 的结点的索引 = \(index)")
+    }
+}

codes/swift/utils/PrintUtil.swift

@@ -15,6 +15,16 @@ public enum PrintUtil {
         }
     }
 
+    public static func printLinkedList(head: ListNode) {
+        var head: ListNode? = head
+        var list: [String] = []
+        while head != nil {
+            list.append("\(head!.val)")
+            head = head?.next
+        }
+        print(list.joined(separator: " -> "))
+    }
+
     public static func printTree(root: TreeNode?) {
         printTree(root: root, prev: nil, isLeft: false)
     }