Added 11 solutions

Java/Data Structures/Java ArrayList/Solution.java

@@ -5,23 +5,20 @@
 import java.util.Scanner;
 import java.util.ArrayList;
 
-/* We need a 2-D array to solve this problem. We can't use an int[][] since we
-   don't know the initial dimensions. So, we use ArrayList<ArrayList<Integer>> */
 public class Solution {
-
     public static void main(String[] args) {
         Scanner scan = new Scanner(System.in);
         int n = scan.nextInt();
                 
         /* Save numbers in 2-D ArrayList */
-        ArrayList<ArrayList<Integer>> list = new ArrayList<>();
+        ArrayList<ArrayList<Integer>> lists = new ArrayList<>();
         for (int row = 0; row < n; row++) {
             int d = scan.nextInt();
-            ArrayList<Integer> numbers = new ArrayList<>();
+            ArrayList<Integer> list = new ArrayList<>();
             for (int col = 0; col < d; col++) {
-                numbers.add(scan.nextInt());
+                list.add(scan.nextInt());
             }
-            list.add(numbers);
+            lists.add(list);
         }
         
         /* Answer the queries */
@@ -29,14 +26,14 @@ public class Solution {
         for (int i = 0; i < q; i++) {
             int x = scan.nextInt();
             int y = scan.nextInt();
-            try {
-                int num = list.get(x-1).get(y-1);
-                System.out.println(num);
-            } catch (IndexOutOfBoundsException e) {
+            ArrayList<Integer> list = lists.get(x-1);
+            if (y <= list.size()) {
+                System.out.println(list.get(y-1));
+            } else {
                 System.out.println("ERROR!");
             }
         }
         
-        scan.close();        
+        scan.close();
     }
 }