Java Arraylist

Sometimes it’s better to use dynamic size arrays. Java’s Arraylist can provide you this feature. Try to solve this problem using Arraylist.

You are given n lines. In each line there are zero or more integers. You need to answer a few queries where you need to tell the number located in y^th position of x^th line.

Take your input from System.in.

Input Format
The first line has an integer n. In each of the next n lines there will be an integer d denoting number of integers on that line and then there will be d space-separated integers. In the next line there will be an integer q denoting number of queries. Each query will consist of two integers x and y.

Constraints

• 1 <= n <= 20000
• 0 <= d <= 50000
• 1 <= q <= 1000
• 1 <= x <= n

Each number will fit in signed integer.
Total number of integers in n lines will not cross 10⁵.

Output Format
In each line, output the number located in y^th position of x^th line. If there is no such position, just print “ERROR!”

Sample Input

5
5 41 77 74 22 44
1 12
4 37 34 36 52
0
3 20 22 33
5
1 3
3 4
3 1
4 3
5 5

Sample Output

74
52
37
ERROR!
ERROR!

Explanation

The diagram below explains the queries:

Solution Implementation

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        List<List<Integer>> lines = new ArrayList<List<Integer>>();
        int n = in.nextInt();
        for (int i = 0; i < n; i++) {
            List<Integer> line = new ArrayList<Integer>();
            int d = in.nextInt();
            for (int j = 0; j < d; j++) {
                line.add(in.nextInt());
            }
            lines.add(line);
        }

        int q = in.nextInt();
        for (int i = 0; i < q; i++) {
            int x = in.nextInt();
            int y = in.nextInt();
            if (y > lines.get(x - 1).size()) {
                System.out.println("ERROR!");
            } else {
                System.out.println(lines.get(x - 1).get(y - 1));
            }
        }

        in.close();
    }
}