Solve the problem #49

Author: rayworks

src/main/java/org/sean/array/AnagramSorter.java

@@ -0,0 +1,56 @@
+package org.sean.array;
+
+import java.util.*;
+
+/** * 49. Group Anagrams */
+public class AnagramSorter {
+    private int[] array = new int[26];
+
+    public List<List<String>> groupAnagrams(String[] strs) {
+        if (strs == null || strs.length == 0) return Collections.emptyList();
+
+        HashMap<String, List<String>> map = new HashMap<>();
+
+        String s = strs[0];
+        List<String> elems = new LinkedList<>();
+        elems.add(s);
+
+        if (strs.length == 1) {
+            return Arrays.asList(elems);
+        }
+
+        String key = extractCountInfo(s);
+        map.put(key, elems);
+
+        for (int i = 1; i < strs.length; i++) {
+            String str = strs[i];
+            String k = extractCountInfo(str);
+            if (map.containsKey(k)) {
+                map.get(k).add(str);
+            } else {
+                List<String> strValues = new LinkedList<>();
+                strValues.add(str);
+                map.put(k, strValues);
+            }
+        }
+
+        return new LinkedList<>(map.values());
+    }
+
+    // Retrieves the character count info e.g '1a3b1c7z'
+    private String extractCountInfo(String s) {
+        Arrays.fill(array, 0);
+
+        for (int m = 0; m < s.length(); m++) {
+            array[s.charAt(m) - 'a'] += 1;
+        }
+
+        StringBuilder builder = new StringBuilder();
+        for (int i = 0; i < array.length; i++) {
+            if (array[i] > 0) {
+                builder.append(array[i]).append((char) ('a' + i));
+            }
+        }
+        return builder.toString();
+    }
+}