290. Word Pattern

Author: TBXark

290. Word Pattern.md

@@ -0,0 +1,47 @@
+# 290. Word Pattern
+
+### 2017-03-13
+
+Given a `pattern` and a string `str`, find if `str` follows the same pattern.
+
+Here **follow** means a full match, such that there is a bijection between a letter in `pattern` and a **non-empty** word in `str`.
+
+**Examples:**
+
+1. pattern = `"abba"`, str = `"dog cat cat dog"` should return true.
+2. pattern = `"abba"`, str = `"dog cat cat fish"` should return false.
+3. pattern = `"aaaa"`, str = `"dog cat cat dog"` should return false.
+4. pattern = `"abba"`, str = `"dog dog dog dog"` should return false.
+
+**Notes:**
+You may assume `pattern` contains only lowercase letters, and `str` contains lowercase letters separated by a single space.
+
+
+
+# Solution
+
+```swift
+class Solution {
+    func wordPattern(_ pattern: String, _ str: String) -> Bool {
+        let array = str.components(separatedBy: " ")
+        guard pattern.characters.count == array.count else { return false }
+        var dict = [String: String]()
+        for (i, char) in pattern.characters.enumerated() {
+            let word = array[i]
+            let c = char.description
+            if let test = dict[c] {
+                guard test == word else { return false }
+            } else  {
+                if dict.values.contains(word) {
+                    return false
+                } else {
+                    dict[c] = word
+                }
+            }
+        }
+        return true
+
+    }
+}
+```
+