feat: add swift implementation to lcof2 problem: No.001 (doocs#2965)

Author: klever34

lcof2/剑指 Offer II 001. 整数除法/README.md

@@ -268,6 +268,36 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func divide(_ a: Int, _ b: Int) -> Int {
+        if b == 1 {
+            return a
+        }
+        if a == Int32.min && b == -1 {
+            return Int(Int32.max)
+        }
+        let sign = (a > 0 && b > 0) || (a < 0 && b < 0)
+        var a = a > 0 ? -a : a
+        let b = b > 0 ? -b : b
+        var ans = 0
+        while a <= b {
+            var x = b
+            var cnt = 1
+            while x >= (Int32.min >> 1) && a <= (x << 1) {
+                x <<= 1
+                cnt <<= 1
+            }
+            ans += cnt
+            a -= x
+        }
+        return sign ? ans : -ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 001. 整数除法/Solution.swift

@@ -0,0 +1,25 @@
+class Solution {
+    func divide(_ a: Int, _ b: Int) -> Int {
+        if b == 1 {
+            return a
+        }
+        if a == Int32.min && b == -1 {
+            return Int(Int32.max)
+        }
+        let sign = (a > 0 && b > 0) || (a < 0 && b < 0)
+        var a = a > 0 ? -a : a
+        let b = b > 0 ? -b : b
+        var ans = 0
+        while a <= b {
+            var x = b
+            var cnt = 1
+            while x >= (Int32.min >> 1) && a <= (x << 1) {
+                x <<= 1
+                cnt <<= 1
+            }
+            ans += cnt
+            a -= x
+        }
+        return sign ? ans : -ans
+    }
+}