feat: implements methods for array concatenation and word search in Lesson11 class

Author: Ezra Nyabuti

lesson_11/arrays_java/arrays_app/src/main/java/com/codedifferently/lesson11/Lesson11.class

@@ -1,5 +1,6 @@
 package com.codedifferently.lesson11;
 
+import java.util.ArrayList;
 import java.util.List;
 
 public class Lesson11 {
@@ -9,14 +10,26 @@ public class Lesson11 {
    * https://leetcode.com/problems/concatenation-of-array
    */
   public int[] getConcatenation(int[] nums) {
-    return null;
+    int answer[] = new int[nums.length * 2];
+    for (int i = 0; i < nums.length; i++) {
+      answer[i] = nums[i];
+      answer[i + nums.length] = nums[i];
+    }
+    return answer;
   }
 
   /**
    * Provide the solution to LeetCode 2942 here:
    * https://leetcode.com/problems/find-words-containing-character/
    */
   public List<Integer> findWordsContaining(String[] words, char x) {
-    return null;
+    List<Integer> result = new ArrayList<>();
+    for (int i = 0; i < words.length; i++) {
+      if (words[i].indexOf(x) != -1) {
+        result.add(i);
+      }
+    }
+
+    return result;
   }
 }