feat: add swift implementation to lcof2 problem: No.090

lcof2/剑指 Offer II 090. 环形房屋偷盗/README.md

@@ -192,6 +192,30 @@ impl Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func rob(_ nums: [Int]) -> Int {
+        let n = nums.count
+        if n == 1 {
+            return nums[0]
+        }
+        return max(rob(nums, 0, n - 2), rob(nums, 1, n - 1))
+    }
+
+    private func rob(_ nums: [Int], _ l: Int, _ r: Int) -> Int {
+        var f = 0, g = 0
+        for i in l...r {
+            let temp = max(f, g)
+            g = f + nums[i]
+            f = temp
+        }
+        return max(f, g)
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 090. 环形房屋偷盗/Solution.swift

@@ -0,0 +1,19 @@
+class Solution {
+    func rob(_ nums: [Int]) -> Int {
+        let n = nums.count
+        if n == 1 {
+            return nums[0]
+        }
+        return max(rob(nums, 0, n - 2), rob(nums, 1, n - 1))
+    }
+
+    private func rob(_ nums: [Int], _ l: Int, _ r: Int) -> Int {
+        var f = 0, g = 0
+        for i in l...r {
+            let temp = max(f, g)
+            g = f + nums[i]
+            f = temp
+        }
+        return max(f, g)
+    }
+}