minor refactorings

Author: rampatra

src/main/java/com/ctci/treesandgraphs/FirstCommonAncestor.java

@@ -5,6 +5,9 @@
  * tree. Avoid storing additional nodes in a data structure. Also, for this question, the tree node
  * does NOT have access to its parent node. NOTE: This is not necessarily a binary search tree.
  *
+ * First Common Ancestor or the Least/Lowest Common Ancestor of two nodes is a node which is the
+ * closest to both of the nodes.
+ *
  * @author rampatra
  * @since 2019-02-24
  */
@@ -18,7 +21,7 @@ public class FirstCommonAncestor {
      * - Returns null, if neither p nor q are in root's subtree.
      * - Else, returns the common ancestor of p and q.
      * <p>
-     * See {@link com.rampatra.trees.LeastCommonAncestorInBT} for a simpler version.
+     * See {@link com.rampatra.trees.LeastCommonAncestorInBT} for a better answer.
      *
      * @param root
      * @param a

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

@@ -2,7 +2,27 @@
 
 /**
  * Level: Easy
- * Problem: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
+ * Link: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
+ * Description:
+ * Say you have an array for which the ith element is the price of a given stock on day i.
+ *
+ * If you were only permitted to complete at most one transaction (i.e., buy one and sell one share of the stock),
+ * design an algorithm to find the maximum profit.
+ *
+ * Note that you cannot sell a stock before you buy one.
+ *
+ * Example 1:
+ *
+ * Input: [7,1,5,3,6,4]
+ * Output: 5
+ * Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
+ *              Not 7-1 = 6, as selling price needs to be larger than buying price.
+ *
+ * Example 2:
+ *
+ * Input: [7,6,4,3,1]
+ * Output: 0
+ * Explanation: In this case, no transaction is done, i.e. max profit = 0.
  *
  * @author rampatra
  * @since 2019-04-23

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

@@ -2,8 +2,8 @@
 
 /**
  * Level: Easy
- * Problem Link: https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
- * Problem Description:
+ * Link: https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
+ * Description:
  * Say you have an array for which the ith element is the price of a given stock on day i.
  * <p>
  * Design an algorithm to find the maximum profit. You may complete as many transactions as you

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

@@ -4,7 +4,20 @@
 
 /**
  * Level: Easy
- * Problem Link: https://leetcode.com/problems/merge-sorted-array/
+ * Link: https://leetcode.com/problems/merge-sorted-array/
+ * Description:
+ * Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
+ *
+ * Note:
+ * The number of elements initialized in nums1 and nums2 are m and n respectively.
+ * You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold
+ * additional elements from nums2.
+ *
+ * Example:
+ * Input:
+ * nums1 = [1,2,3,0,0,0], m = 3
+ * nums2 = [2,5,6],       n = 3
+ * Output: [1,2,2,3,5,6]
  *
  * @author rampatra
  * @since 2019-04-26

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

@@ -4,7 +4,28 @@
 
 /**
  * Level: Easy
- * Problem: https://leetcode.com/problems/rotate-array/
+ * Link: https://leetcode.com/problems/rotate-array/
+ * Description:
+ * Given an array, rotate the array to the right by k steps, where k is non-negative.
+ *
+ * Example 1:
+ * Input: [1,2,3,4,5,6,7] and k = 3
+ * Output: [5,6,7,1,2,3,4]
+ * Explanation:
+ * rotate 1 steps to the right: [7,1,2,3,4,5,6]
+ * rotate 2 steps to the right: [6,7,1,2,3,4,5]
+ * rotate 3 steps to the right: [5,6,7,1,2,3,4]
+ *
+ * Example 2:
+ * Input: [-1,-100,3,99] and k = 2
+ * Output: [3,99,-1,-100]
+ * Explanation:
+ * rotate 1 steps to the right: [99,-1,-100,3]
+ * rotate 2 steps to the right: [3,99,-1,-100]
+ *
+ * Note:
+ * Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
+ * Could you do it in-place with O(1) extra space?
  *
  * @author rampatra
  * @since 2019-04-20