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  1. Prepare
  2. Java
  3. Data Structures
  4. Java List
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Java List

  • RodneyShag
     + 38 comments

    Java solution - passes 100% of test cases

    Use a LinkedList instead of an ArrayList when adding/removing items often since it will be faster (ArrayList often needs to shift O(n) elements after an add or remove, which is slow).

    From my HackerRank solutions.

    import java.util.Scanner;
import java.util.LinkedList;

public class Solution {
    public static void main(String[] args) {
        /* Create and fill Linked List of Integers */
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        LinkedList<Integer> list = new LinkedList<>();
        for (int i = 0; i < N; i++) {
            int value = scan.nextInt();
            list.add(value);
        }
        
        /* Perfrom queries on Linked List */
        int Q = scan.nextInt();
        for (int i = 0; i < Q; i++) {
            String action = scan.next();
            if (action.equals("Insert")) {
                int index = scan.nextInt();
                int value = scan.nextInt();
                list.add(index, value);
            } else { // "Delete"
                int index = scan.nextInt();
                list.remove(index);
            }
        }
        scan.close();
        
        /* Print our updated Linked List */
        for (Integer num : list) {
            System.out.print(num + " ");
        }
    }
}

    Let me know if you have any questions.