feat: add swift implementation to lcof2 problem: No.030 (#3035)

Author: klever34

lcof2/剑指 Offer II 030. 插入、删除和随机访问都是 O(1) 的容器/README.md

@@ -217,6 +217,54 @@ public:
  */
 ```
 
+#### Swift
+
+```swift
+class RandomizedSet {
+    private var m: [Int: Int]
+    private var a: [Int]
+    
+    init() {
+        self.m = [Int: Int]()
+        self.a = [Int]()
+    }
+    
+    func insert(_ val: Int) -> Bool {
+        if m[val] != nil {
+            return false
+        }
+        m[val] = a.count
+        a.append(val)
+        return true
+    }
+    
+    func remove(_ val: Int) -> Bool {
+        if let idx = m[val] {
+            let last = a.count - 1
+            if idx != last {
+                a.swapAt(idx, last)
+                m[a[idx]] = idx
+            }
+            a.removeLast()
+            m.removeValue(forKey: val)
+            return true
+        }
+        return false
+    }
+    
+    func getRandom() -> Int {
+        return a[Int.random(in: 0..<a.count)]
+    }
+}
+
+/* let obj = RandomizedSet()
+* let param_1 = obj.insert(val)
+* let param_2 = obj.insert(val)
+* let param_3 = obj.remove(val)
+* let param_4 = obj.getRandom()
+*/
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 030. 插入、删除和随机访问都是 O(1) 的容器/Solution.swift

@@ -0,0 +1,43 @@
+class RandomizedSet {
+    private var m: [Int: Int]
+    private var a: [Int]
+    
+    init() {
+        self.m = [Int: Int]()
+        self.a = [Int]()
+    }
+    
+    func insert(_ val: Int) -> Bool {
+        if m[val] != nil {
+            return false
+        }
+        m[val] = a.count
+        a.append(val)
+        return true
+    }
+    
+    func remove(_ val: Int) -> Bool {
+        if let idx = m[val] {
+            let last = a.count - 1
+            if idx != last {
+                a.swapAt(idx, last)
+                m[a[idx]] = idx
+            }
+            a.removeLast()
+            m.removeValue(forKey: val)
+            return true
+        }
+        return false
+    }
+    
+    func getRandom() -> Int {
+        return a[Int.random(in: 0..<a.count)]
+    }
+}
+
+/* let obj = RandomizedSet()
+* let param_1 = obj.insert(val)
+* let param_2 = obj.insert(val)
+* let param_3 = obj.remove(val)
+* let param_4 = obj.getRandom()
+*/