46. Group Anagrams

Author: NilStack

README.md

@@ -6,6 +6,7 @@ Not only Leetcode solutions in Swift.
 * [15. 3Sum](https://leetcode.com/problems/3sum/)
 * [16. 3Sum Closest](https://leetcode.com/problems/3sum-closest/)
 * [18. 4Sum](https://leetcode.com/problems/4sum/)
+* [46. Group Anagrams](https://leetcode.com/problems/anagrams/)
 * [167. Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/)
 * [170. Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design)
 * [Two Sum - Less than or equal to target](http://www.lintcode.com/en/problem/two-sum-less-than-or-equal-to-target/)

SwiftyLeetCode.playground/Contents.swift

@@ -200,6 +200,33 @@ let fourSumNums = [1, 0, -1, 0, -2, 2]
 let fourSumTarget = 0
 Solution.fourSum(nums: fourSumNums, fourSumTarget)
 
+/**
+ * 49. Group Anagrams
+ * https://leetcode.com/problems/anagrams/
+ */
+
+extension Solution {
+    class func groupAnagrams(strs: [String]?) -> [[String]]? {
+        guard let strs = strs, strs.count > 0 else { return nil }
+        
+        var map = [String: [String]]()
+        strs.forEach { str in
+            let kStr = String(str.characters.sorted())
+            if(map[kStr] == nil) {
+                map[kStr] = [String]()
+            }
+            map[kStr]!.append(str)
+        }
+        
+        return Array(Array(map.values))
+    }
+}
+
+// usage
+
+let groupAnagramsStrs = ["eat", "tea", "tan", "ate", "nat", "bat"]
+Solution.groupAnagrams(strs: groupAnagramsStrs)
+
 /**
  * 167. Two Sum II - Input array is sorted
  * https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/