[N-0] refactor 17

fishercoder1534 · fishercoder1534 · commit 147c4a5abb7a · 2017-10-29T21:52:09.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_17.java b/src/main/java/com/fishercoder/solutions/_17.java
@@ -18,31 +18,33 @@
 
 public class _17 {
 
-    public List<String> letterCombinations(String digits) {
-        List<String> result = new ArrayList();
-        if (digits.length() == 0) {
-            return result;
-        }
+    public static class Solution1 {
+        public List<String> letterCombinations(String digits) {
+            List<String> result = new ArrayList();
+            if (digits.length() == 0) {
+                return result;
+            }
 
-        String[] digits2Letters = new String[]{"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
+            String[] digits2Letters = new String[]{"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
 
-        result.add("");//this line is important, otherwise result is empty and Java will default it to an empty String
-        for (int i = 0; i < digits.length(); i++) {
-            result = combine(digits2Letters[digits.charAt(i) - '0'], result);
-        }
+            result.add("");//this line is important, otherwise result is empty and Java will default it to an empty String
+            for (int i = 0; i < digits.length(); i++) {
+                result = combine(digits2Letters[digits.charAt(i) - '0'], result);
+            }
 
-        return result;
-    }
+            return result;
+        }
 
-    List<String> combine(String letters, List<String> result) {
-        List<String> newResult = new ArrayList();
+        List<String> combine(String letters, List<String> result) {
+            List<String> newResult = new ArrayList();
 
-        for (int i = 0; i < letters.length(); i++) {
-            //the order of the two for loops doesn't matter, you could swap them and it still works.
-            for (String str : result) {
-                newResult.add(str + letters.charAt(i));
+            for (int i = 0; i < letters.length(); i++) {
+                //the order of the two for loops doesn't matter, you could swap them and it still works.
+                for (String str : result) {
+                    newResult.add(str + letters.charAt(i));
+                }
             }
+            return newResult;
         }
-        return newResult;
     }
 }
diff --git a/src/test/java/com/fishercoder/_17Test.java b/src/test/java/com/fishercoder/_17Test.java
@@ -12,28 +12,28 @@
 import static org.junit.Assert.assertTrue;
 
 public class _17Test {
-    private static _17 test;
+    private static _17.Solution1 solution1;
     private static String digits;
     private static List<String> expected;
     private static List<String> actual;
 
     @BeforeClass
     public static void setup() {
-        test = new _17();
+        solution1 = new _17.Solution1();
     }
 
     @Test
     public void test1() {
         digits = "2";
-        actual = test.letterCombinations(digits);
+        actual = solution1.letterCombinations(digits);
         expected = new ArrayList<>(Arrays.asList("a", "b", "c"));
         assertEquals(expected, actual);
     }
 
     @Test
     public void test2() {
         digits = "23";
-        actual = test.letterCombinations(digits);
+        actual = solution1.letterCombinations(digits);
         expected = new ArrayList<>(Arrays.asList("ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"));
         /**order doesn't matter, so we check like below*/
         assertTrue(expected.containsAll(actual) && actual.containsAll(expected));
