feat: add swift implementation to lcof2 problem: No.005 (#2975)

Author: klever34

lcof2/剑指 Offer II 005. 单词长度的最大乘积/README.md

@@ -181,6 +181,34 @@ function maxProduct(words: string[]): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func maxProduct(_ words: [String]) -> Int {
+        let n = words.count
+        var masks = [Int](repeating: 0, count: n)
+        
+        for i in 0..<n {
+            for c in words[i] {
+                masks[i] |= 1 << (c.asciiValue! - Character("a").asciiValue!)
+            }
+        }
+        
+        var maxProduct = 0
+        for i in 0..<n {
+            for j in i+1..<n {
+                if masks[i] & masks[j] == 0 {
+                    maxProduct = max(maxProduct, words[i].count * words[j].count)
+                }
+            }
+        }
+        
+        return maxProduct
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 005. 单词长度的最大乘积/Solution.swift

@@ -0,0 +1,23 @@
+class Solution {
+    func maxProduct(_ words: [String]) -> Int {
+        let n = words.count
+        var masks = [Int](repeating: 0, count: n)
+        
+        for i in 0..<n {
+            for c in words[i] {
+                masks[i] |= 1 << (c.asciiValue! - Character("a").asciiValue!)
+            }
+        }
+        
+        var maxProduct = 0
+        for i in 0..<n {
+            for j in i+1..<n {
+                if masks[i] & masks[j] == 0 {
+                    maxProduct = max(maxProduct, words[i].count * words[j].count)
+                }
+            }
+        }
+        
+        return maxProduct
+    }
+}