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Author: dingjikerbo

README.md

@@ -228,6 +228,7 @@
 |245|[Shortest Word Distance III](https://leetcode.com/problems/shortest-word-distance-iii/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/ShortestWordDistanceIII.java)|80||
 |246|[Strobogrammatic Number](https://leetcode.com/problems/strobogrammatic-number/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/StrobogrammaticNumber.java)|70|#247一个系列，多看两遍|
 |247|[Strobogrammatic Number II](https://leetcode.com/problems/strobogrammatic-number-ii/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/StrobogrammaticNumberII.java)|70|多看两遍|
+|249|[Group Shifted Strings](https://leetcode.com/problems/group-shifted-strings/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/GroupShiftedStrings.java)||
 |250|[Count Univalue Subtrees](https://leetcode.com/problems/count-univalue-subtrees/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/CountUnivalueSubtrees.java)|70|这题要多做几遍|
 |251|[Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/Vector2D.java)|100|
 |252|[Meeting Rooms](https://leetcode.com/problems/meeting-rooms/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/MeetingRooms.java)|100|

solution/src/main/java/com/inuker/solution/GroupShiftedStrings.java

@@ -0,0 +1,49 @@
+package com.inuker.solution;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Created by liwentian on 2017/12/9.
+ */
+
+public class GroupShiftedStrings {
+    /**
+     * 这里核心是getTag，不论怎么shift，都回滚到a开头
+     */
+    public List<List<String>> groupStrings(String[] strings) {
+        Map<String, List<String>> map = new HashMap<>();
+
+        for (String s : strings) {
+            String key = getTag(s);
+            List<String> value = map.get(key);
+            if (value == null) {
+                value = new ArrayList<>();
+                map.put(key, value);
+            }
+
+            value.add(s);
+        }
+
+        List<List<String>> ret = new ArrayList<>();
+        for (List<String> lst : map.values()) {
+            Collections.sort(lst); // dont forget to sort.
+            ret.add(lst);
+        }
+
+        return ret;
+    }
+
+    String getTag(String s) {
+        int diff = (int) s.charAt(0) - (int) 'a';
+
+        StringBuilder sb = new StringBuilder();
+        for (char c : s.toCharArray())
+            sb.append((c + 26 - diff) % 26);
+
+        return sb.toString();
+    }
+}

test/src/main/java/com/inuker/test/main.java

@@ -28,6 +28,18 @@
 public class main {
 
     public static void main(String[] args) {
+        System.out.println(getTag("abc"));
+        System.out.println(getTag("bcd"));
+        System.out.println(getTag("cde"));
     }
 
+    static String getTag(String s) {
+        int diff = (int) s.charAt(0) - (int) 'a';
+
+        StringBuilder sb = new StringBuilder();
+        for (char c : s.toCharArray())
+            sb.append((c + 26 - diff) % 26);
+
+        return sb.toString();
+    }
 }