feat: add swift implementation to lcci problem: No.17.11 (doocs#2783)

Author: klever34

lcci/17.11.Find Closest/README.md

@@ -137,6 +137,28 @@ impl Solution {
 }
 ```
 
+```swift
+class Solution {
+    func findClosest(_ words: [String], _ word1: String, _ word2: String) -> Int {
+        let inf = Int.max / 2
+        var i = inf
+        var j = -inf
+        var ans = inf
+
+        for (k, word) in words.enumerated() {
+            if word == word1 {
+                i = k
+            } else if word == word2 {
+                j = k
+            }
+            ans = min(ans, abs(i - j))
+        }
+
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 ### 方法二：哈希表 + 双指针

lcci/17.11.Find Closest/README_EN.md

@@ -139,6 +139,28 @@ impl Solution {
 }
 ```
 
+```swift
+class Solution {
+    func findClosest(_ words: [String], _ word1: String, _ word2: String) -> Int {
+        let inf = Int.max / 2
+        var i = inf
+        var j = -inf
+        var ans = inf
+
+        for (k, word) in words.enumerated() {
+            if word == word1 {
+                i = k
+            } else if word == word2 {
+                j = k
+            }
+            ans = min(ans, abs(i - j))
+        }
+
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 ### Solution 2: Hash Table + Two Pointers

lcci/17.11.Find Closest/Solution.swift

@@ -0,0 +1,19 @@
+class Solution {
+    func findClosest(_ words: [String], _ word1: String, _ word2: String) -> Int {
+        let inf = Int.max / 2
+        var i = inf
+        var j = -inf
+        var ans = inf
+
+        for (k, word) in words.enumerated() {
+            if word == word1 {
+                i = k
+            } else if word == word2 {
+                j = k
+            }
+            ans = min(ans, abs(i - j))
+        }
+
+        return ans
+    }
+}