coded + unit tested

Author: Ram swaroop

src/me/ramswaroop/strings/StringRotation.java

@@ -0,0 +1,53 @@
+package me.ramswaroop.strings;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 10/21/15
+ * @time: 10:06 AM
+ * @see: me.ramswaroop.strings.SubString for a similar problem.
+ */
+public class StringRotation {
+
+    /**
+     * Determines if string {@param s2} is a rotation of string {@param s1}.
+     *
+     * @param s1
+     * @param s2
+     * @return
+     */
+    public static boolean isStringRotation(String s1, String s2) {
+        char[] c1 = s1.toCharArray();
+        char[] c2 = s2.toCharArray();
+
+        int l1 = c1.length,
+                l2 = c2.length,
+                i, j, k;
+
+        for (i = 0; i < l1; i++) {
+            for (j = 0; j < l2 && i + j < l1; j++) {
+                if (c1[i + j] != c2[j]) break;
+            }
+            k = 0;
+            while (k < l1 && j < l2) {
+                if (c1[k++] != c2[j]) break;
+                j++;
+            }
+            if (j == l2) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static void main(String a[]) {
+        System.out.println(isStringRotation("ramswaroop", "swaroopram"));
+        System.out.println(isStringRotation("ramswaroop", "swaroopramramram"));
+        System.out.println(isStringRotation("ramswaroop", "mswaroopra"));
+        System.out.println(isStringRotation("ramswaroop", "swarooppram"));
+        System.out.println(isStringRotation("ramswaroop", ""));
+        System.out.println(isStringRotation("mswaroopra", "ramswaroop"));
+        System.out.println(isStringRotation("amam", "mama"));
+    }
+}

src/me/ramswaroop/strings/SubString.java

@@ -6,6 +6,7 @@
  * @author: ramswaroop
  * @date: 10/20/15
  * @time: 1:15 PM
+ * @see: me.ramswaroop.strings.StringRotation for a similar problem.
  */
 public class SubString {
 
@@ -36,6 +37,8 @@ public static boolean isSubString(String s1, String s2) {
     }
 
     public static void main(String a[]) {
+        System.out.println(isSubString("ramswaroop", "ramswaroop"));
+        System.out.println(isSubString("ramswaroop", ""));
         System.out.println(isSubString("ramswaroop", "ram"));
         System.out.println(isSubString("ramswaroop", "rams"));
         System.out.println(isSubString("ramswaroop", "ramss"));