[String] Add a solution to Shortest Distance to a Character

Author: soapyigu

README.md

@@ -28,7 +28,7 @@
 * [Microsoft](#microsoft)
 
 ## Progress
-[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 258 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
+[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 259 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
 
 
 ## Array
@@ -96,6 +96,7 @@
 [Length of Last Word](https://leetcode.com/problems/length-of-last-word/)| [Swift](./String/AddStrings.swift)| Easy| O(n)| O(n)|
 [String Compression](https://leetcode.com/problems/string-compression/)| [Swift](./String/StringCompression.swift)| Easy| O(n)| O(1)|
 [Add Strings](https://leetcode.com/problems/add-strings/)| [Swift](./String/LengthLastWord.swift)| Easy| O(n)| O(1)|
+[Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character/)| [Swift](./String/ShortestDistanceToACharacter.swift)| Easy| O(n)| O(1)|
 [Multiply Strings](https://leetcode.com/problems/multiply-strings/)| [Swift](./String/MultiplyStrings.swift)| Medium| O(n)| O(1)|
 [Palindrome Permutation](https://leetcode.com/problems/palindrome-permutation/)| [Swift](./String/PalindromePermutation.swift)| Easy| O(n)| O(n)|
 [Valid Anagram](https://leetcode.com/problems/valid-anagram/)| [Swift](./String/ValidAnagram.swift)| Easy| O(nlogn)| O(1)|

String/ShortestDistanceToACharacter.swift

@@ -0,0 +1,35 @@
+/**
+ * Question Link: https://leetcode.com/problems/shortest-distance-to-a-character/
+ * Primary idea: Iterate through left and right to get min distance by compared between indices of C at two sides.
+ *
+ * Time Complexity: O(n), Space Complexity: O(1)
+ *
+ */
+
+ class ShortestDistanceToACharacter {
+    func shortestToChar(_ S: String, _ C: Character) -> [Int] {
+        var res = Array(repeating: 0, count: S.count), cIndex = -10000, sChars = Array(S)
+        
+        for (i, sChar) in sChars.enumerated() {
+            if sChar == C {
+                cIndex = i
+            }
+            
+            res[i] = i - cIndex
+        }
+        
+        cIndex = -10000
+        
+        for i in (0..<sChars.count).reversed() {
+            let currentChar = sChars[i]
+            
+            if currentChar == C {
+                cIndex = i
+            }
+            
+            res[i] = min(res[i], abs(cIndex - i))
+        }
+        
+        return res
+    }
+}