feat: add swift implementation to lcci problem: No.03.03 (doocs#2641)

Author: klever34

lcci/03.03.Stack of Plates/README.md

@@ -258,6 +258,51 @@ class StackOfPlates {
  */
 ```
 
+```swift
+class StackOfPlates {
+    private var stacks: [[Int]]
+    private var cap: Int
+
+    init(_ cap: Int) {
+        self.cap = cap
+        self.stacks = []
+    }
+
+    func push(_ val: Int) {
+        if cap == 0 {
+            return
+        }
+        if stacks.isEmpty || stacks.last!.count >= cap {
+            stacks.append([])
+        }
+        stacks[stacks.count - 1].append(val)
+    }
+
+    func pop() -> Int {
+        return popAt(stacks.count - 1)
+    }
+
+    func popAt(_ index: Int) -> Int {
+        guard index >= 0, index < stacks.count, !stacks[index].isEmpty else {
+            return -1
+        }
+        let value = stacks[index].removeLast()
+        if stacks[index].isEmpty {
+            stacks.remove(at: index)
+        }
+        return value
+    }
+}
+
+/**
+ * Your StackOfPlates object will be instantiated and called as such:
+ * let obj = new StackOfPlates(cap);
+ * obj.push(val);
+ * let param_2 = obj.pop();
+ * let param_3 = obj.popAt(index);
+ */
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/03.03.Stack of Plates/README_EN.md

@@ -273,6 +273,51 @@ class StackOfPlates {
  */
 ```
 
+```swift
+class StackOfPlates {
+    private var stacks: [[Int]]
+    private var cap: Int
+
+    init(_ cap: Int) {
+        self.cap = cap
+        self.stacks = []
+    }
+
+    func push(_ val: Int) {
+        if cap == 0 {
+            return
+        }
+        if stacks.isEmpty || stacks.last!.count >= cap {
+            stacks.append([])
+        }
+        stacks[stacks.count - 1].append(val)
+    }
+
+    func pop() -> Int {
+        return popAt(stacks.count - 1)
+    }
+
+    func popAt(_ index: Int) -> Int {
+        guard index >= 0, index < stacks.count, !stacks[index].isEmpty else {
+            return -1
+        }
+        let value = stacks[index].removeLast()
+        if stacks[index].isEmpty {
+            stacks.remove(at: index)
+        }
+        return value
+    }
+}
+
+/**
+ * Your StackOfPlates object will be instantiated and called as such:
+ * let obj = new StackOfPlates(cap);
+ * obj.push(val);
+ * let param_2 = obj.pop();
+ * let param_3 = obj.popAt(index);
+ */
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/03.03.Stack of Plates/Solution.swift

@@ -0,0 +1,42 @@
+class StackOfPlates {
+    private var stacks: [[Int]]
+    private var cap: Int
+
+    init(_ cap: Int) {
+        self.cap = cap
+        self.stacks = []
+    }
+
+    func push(_ val: Int) {
+        if cap == 0 {
+            return
+        }
+        if stacks.isEmpty || stacks.last!.count >= cap {
+            stacks.append([])
+        }
+        stacks[stacks.count - 1].append(val)
+    }
+
+    func pop() -> Int {
+        return popAt(stacks.count - 1)
+    }
+
+    func popAt(_ index: Int) -> Int {
+        guard index >= 0, index < stacks.count, !stacks[index].isEmpty else {
+            return -1
+        }
+        let value = stacks[index].removeLast()
+        if stacks[index].isEmpty {
+            stacks.remove(at: index)
+        }
+        return value
+    }
+}
+
+/**
+ * Your StackOfPlates object will be instantiated and called as such:
+ * let obj = new StackOfPlates(cap);
+ * obj.push(val);
+ * let param_2 = obj.pop();
+ * let param_3 = obj.popAt(index);
+ */