add 6 lesson

6l_ChukarkovKonstantin.playground/Contents.swift

@@ -0,0 +1,45 @@
+
+struct Stack<Element> {
+
+    var items = [Element]()
+    mutating func push(_ item: Element) {
+        items.append(item)
+    }
+
+    mutating func pop() -> Element {
+        return items.removeLast()
+    }
+
+    mutating func append(_ item: Element) {
+        self.push(item)
+    }
+
+
+    var count: Int {
+        return items.count
+    }
+
+    subscript(i: Int) -> Element? {
+        if i < items.count {
+            return items[i]
+        }
+        return nil
+    }
+
+}
+
+
+var stack = Stack<String>()
+
+stack.push("кот")
+stack.push("бегемот")
+stack.push("жираф")
+stack.push("крыса")
+
+stack.pop()
+
+print(stack.count)
+
+
+print(stack[1]!)
+print(stack[4] as Any)

6l_ChukarkovKonstantin.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>