Rotate array done + some minor refactorings

Author: rampatra

src/main/java/com/leetcode/arrays/RotateArray.java

@@ -0,0 +1,71 @@
+package com.leetcode.arrays;
+
+import java.util.Arrays;
+
+/**
+ * Problem: https://leetcode.com/problems/rotate-array/
+ *
+ * @author rampatra
+ * @since 2019-04-20
+ */
+public class RotateArray {
+
+    /**
+     * Time complexity: O(n)
+     * where,
+     * n = no. of elements in the array
+     * <p>
+     * Runtime: <a href="https://leetcode.com/submissions/detail/224425565/">0 ms</a>.
+     *
+     * @param nums
+     * @param k
+     */
+    public static void rotate(int[] nums, int k) {
+
+        if (k > nums.length) {
+            k = k % nums.length;
+        }
+        
+        reverse(nums, 0, nums.length);
+        reverse(nums, 0, k);
+        reverse(nums, k, nums.length);
+    }
+
+    private static void reverse(int[] nums, int start, int end) {
+        int temp;
+        for (int i = start, j = end - 1; i < j; i++, j--) {
+            temp = nums[i];
+            nums[i] = nums[j];
+            nums[j] = temp;
+        }
+    }
+
+    public static void main(String[] args) {
+        // normal case
+        int[] arr = {1, 2, 3, 4, 5, 6, 7};
+        System.out.println(Arrays.toString(arr));
+        rotate(arr, 3);
+        System.out.println(Arrays.toString(arr));
+
+        // edge cases
+        arr = new int[]{1, 2};
+        System.out.println(Arrays.toString(arr));
+        rotate(arr, 2);
+        System.out.println(Arrays.toString(arr)); // should be [1, 2]
+
+        arr = new int[]{1, 2};
+        System.out.println(Arrays.toString(arr));
+        rotate(arr, 3);
+        System.out.println(Arrays.toString(arr)); // should be [2, 1]
+
+        arr = new int[]{1, 2, 3};
+        System.out.println(Arrays.toString(arr));
+        rotate(arr, 4);
+        System.out.println(Arrays.toString(arr)); // should be [3, 1, 2]
+
+        arr = new int[]{1};
+        System.out.println(Arrays.toString(arr));
+        rotate(arr, 2);
+        System.out.println(Arrays.toString(arr));
+    }
+}

src/main/java/com/leetcode/strings/AnagramsInString.java

@@ -5,7 +5,7 @@
 import java.util.List;
 
 /**
- * Leetcode Problem: https://leetcode.com/problems/find-all-anagrams-in-a-string/
+ * Problem: https://leetcode.com/problems/find-all-anagrams-in-a-string/
  *
  * @author rampatra
  * @since 2019-04-13

src/main/java/com/leetcode/strings/ReverseVowels.java

@@ -1,7 +1,7 @@
 package com.leetcode.strings;
 
 /**
- * Leetcode Problem: https://leetcode.com/problems/reverse-vowels-of-a-string/
+ * Problem: https://leetcode.com/problems/reverse-vowels-of-a-string/
  *
  * @author rampatra
  * @since 2019-04-19

src/main/java/com/leetcode/strings/UniqueCharacterInString.java

@@ -1,7 +1,7 @@
 package com.leetcode.strings;
 
 /**
- * Leetcode Problem: https://leetcode.com/problems/first-unique-character-in-a-string/
+ * Problem: https://leetcode.com/problems/first-unique-character-in-a-string/
  *
  * @author rampatra
  * @since 2019-04-16

src/main/java/com/leetcode/strings/ValidPalindrome.java

@@ -1,6 +1,8 @@
 package com.leetcode.strings;
 
 /**
+ * Problem: https://leetcode.com/problems/valid-palindrome/
+ *
  * @author rampatra
  * @since 2019-04-19
  */

src/main/java/com/leetcode/trie/LongestWord.java

@@ -4,7 +4,7 @@
 import java.util.Stack;
 
 /**
- * Leetcode Problem: https://leetcode.com/problems/longest-word-in-dictionary/
+ * Problem: https://leetcode.com/problems/longest-word-in-dictionary/
  *
  * @author rampatra
  * @since 2019-04-10