feat: add swift implementation to lcci problem: No.17.01 (doocs#2771)

Author: klever34

lcci/17.01.Add Without Plus/README.md

@@ -43,6 +43,26 @@ class Solution {
 }
 ```
 
+```swift
+class Solution {
+    func add(_ a: Int, _ b: Int) -> Int {
+        var a = a
+        var b = b
+        var sum = 0
+        var carry = 0
+        
+        while b != 0 {
+            sum = a ^ b
+            carry = (a & b) << 1
+            a = sum
+            b = carry
+        }
+        
+        return a
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/17.01.Add Without Plus/README_EN.md

@@ -44,6 +44,26 @@ class Solution {
 }
 ```
 
+```swift
+class Solution {
+    func add(_ a: Int, _ b: Int) -> Int {
+        var a = a
+        var b = b
+        var sum = 0
+        var carry = 0
+        
+        while b != 0 {
+            sum = a ^ b
+            carry = (a & b) << 1
+            a = sum
+            b = carry
+        }
+        
+        return a
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/17.01.Add Without Plus/Solution.swift

@@ -0,0 +1,17 @@
+class Solution {
+    func add(_ a: Int, _ b: Int) -> Int {
+        var a = a
+        var b = b
+        var sum = 0
+        var carry = 0
+        
+        while b != 0 {
+            sum = a ^ b
+            carry = (a & b) << 1
+            a = sum
+            b = carry
+        }
+        
+        return a
+    }
+}