refactor 87

Author: fishercoder1534

README.md

@@ -602,7 +602,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |90|[Subsets II](https://leetcode.com/problems/subsets-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_90.java)|O(n^2) |O(1)||Medium|Backtracking
 |89|[Gray Code](https://leetcode.com/problems/gray-code/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_89.java)|O(n) |O(1)||Medium|Bit Manipulation
 |88|[Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_88.java)|O(max(m,n)) |O(1)||Easy|
-|87|[Scramble String](https://leetcode.com/problems/scramble-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_87.java)|O(?) |O(?)||Hard| Recursion
+|87|[Scramble String](https://leetcode.com/problems/scramble-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_87.java)|O(n^4) |O(n^3||Hard| Recursion
 |86|[Partition List](https://leetcode.com/problems/partition-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_86.java)|O(n) |O(1)||Medium| Linked List
 |85|[Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_85.java)|O(m*n) |O(n)||Hard|DP
 |84|[Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_84.java)|O(n) |O(n)||Hard|Array, Stack

src/main/java/com/fishercoder/solutions/_87.java

@@ -42,34 +42,39 @@
  */
 public class _87 {
 
-    /**credit: https://discuss.leetcode.com/topic/19158/accepted-java-solution*/
-    public boolean isScramble(String s1, String s2) {
-        if (s1.equals(s2)) {
+    public static class Solution1 {
+        /** credit: https://discuss.leetcode.com/topic/19158/accepted-java-solution */
+        public boolean isScramble(String s1, String s2) {
+          if (s1.equals(s2)) {
             return true;
-        }
+          }
+          if (s1.length() != s2.length()) {
+            return false;
+          }
 
-        int[] letters = new int[26];
-        for (int i = 0; i < s1.length(); i++) {
+          int[] letters = new int[26];
+          for (int i = 0; i < s1.length(); i++) {
             letters[s1.charAt(i) - 'a']++;
             letters[s2.charAt(i) - 'a']--;
-        }
+          }
 
-        for (int i : letters) {
+          for (int i : letters) {
             if (i != 0) {
-                return false;
+              return false;
             }
-        }
+          }
 
-        for (int i = 1; i < s1.length(); i++) {
-            if (isScramble(s1.substring(0, i), s2.substring(0, i)) && isScramble(s1.substring(i), s2.substring(i))) {
-                return true;
+          for (int i = 1; i < s1.length(); i++) {
+            if (isScramble(s1.substring(0, i), s2.substring(0, i)) && isScramble(
+                s1.substring(i), s2.substring(i))) {
+              return true;
             }
-            if (isScramble(s1.substring(0, i), s2.substring(s2.length() - i)) && isScramble(s1.substring(i), s2.substring(0, s2.length() - i))) {
-                return true;
+            if (isScramble(s1.substring(0, i), s2.substring(s2.length() - i)) && isScramble(
+                s1.substring(i), s2.substring(0, s2.length() - i))) {
+              return true;
             }
+          }
+          return false;
         }
-
-        return false;
     }
-
 }

src/test/java/com/fishercoder/_87Test.java

@@ -6,30 +6,26 @@
 
 import static org.junit.Assert.assertEquals;
 
-/**
- * Created by stevesun on 6/4/17.
- */
 public class _87Test {
-    private static _87 test;
-
-    @BeforeClass
-    public static void setup() {
-        test = new _87();
-    }
-
-    @Test
-    public void test1() {
-        assertEquals(true, test.isScramble("great", "rgeat"));
-    }
-
-    @Test
-    public void test2() {
-        assertEquals(true, test.isScramble("great", "rgtae"));
-    }
-
-    @Test
-    public void test3() {
-        assertEquals(true, test.isScramble("abc", "bca"));
-    }
-
+  private static _87.Solution1 solution1;
+
+  @BeforeClass
+  public static void setup() {
+    solution1 = new _87.Solution1();
+  }
+
+  @Test
+  public void test1() {
+    assertEquals(true, solution1.isScramble("great", "rgeat"));
+  }
+
+  @Test
+  public void test2() {
+    assertEquals(true, solution1.isScramble("great", "rgtae"));
+  }
+
+  @Test
+  public void test3() {
+    assertEquals(true, solution1.isScramble("abc", "bca"));
+  }
 }