Add a solution to Guess Word

Author: soapyigu

Design/GuessWord.swift

@@ -0,0 +1,48 @@
+/**
+ * Question Link: https://leetcode.com/problems/guess-the-word/
+ * Primary idea: Random select a word and check the match count. Filter all words having the same match count.
+ *
+ * Time Complexity: O(n), Space Complexity: O(n)
+ *
+ * // This is the Master's API interface.
+ * // You should not implement it, or speculate about its implementation
+ * class Master {
+ *     public func guess(word: String) -> Int {}
+ * }
+ */
+
+class GuessWord {
+    func findSecretWord(_ words: [String], _ master: Master) {
+        var words = words
+        
+        for i in 0..<30 {
+            let trial = words[words.count / 2]
+            let count = master.guess(trial)
+            
+            if count == 6 {
+                return
+            }
+            
+            var possibilities = [String]()
+            for word in words {
+                if matchCount(trial, word) == count {
+                    possibilities.append(word)
+                }
+            }
+            words = possibilities
+        }
+        
+    }
+    
+    private func matchCount(_ wordA: String, _ wordB: String) -> Int {
+        var res = 0
+    
+        for (charA, charB) in zip(wordA, wordB) {
+            if charA == charB {
+                res += 1
+            }
+        }
+        
+        return res
+    }
+}