feat: add swift implementation to lcci problem: No.05.02 (doocs#2666)

Author: klever34

lcci/05.02.Binary Number to String/README.md

@@ -108,6 +108,24 @@ func printBin(num float64) string {
 }
 ```
 
+```swift
+class Solution {
+    func printBin(_ num: Double) -> String {
+        var num = num
+        var ans = "0."
+
+        while ans.count < 32 && num != 0 {
+            num *= 2
+            let x = Int(num)
+            ans.append("\(x)")
+            num -= Double(x)
+        }
+
+        return num != 0 ? "ERROR" : ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/05.02.Binary Number to String/README_EN.md

@@ -115,6 +115,24 @@ func printBin(num float64) string {
 }
 ```
 
+```swift
+class Solution {
+    func printBin(_ num: Double) -> String {
+        var num = num
+        var ans = "0."
+
+        while ans.count < 32 && num != 0 {
+            num *= 2
+            let x = Int(num)
+            ans.append("\(x)")
+            num -= Double(x)
+        }
+
+        return num != 0 ? "ERROR" : ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/05.02.Binary Number to String/Solution.swift

@@ -0,0 +1,15 @@
+class Solution {
+    func printBin(_ num: Double) -> String {
+        var num = num
+        var ans = "0."
+        
+        while ans.count < 32 && num != 0 {
+            num *= 2
+            let x = Int(num)
+            ans.append("\(x)")
+            num -= Double(x)
+        }
+        
+        return num != 0 ? "ERROR" : ans
+    }
+}