Lec 02 - Sorting

Default Sorting

In Java, the sorting is implemented in

1. Collections (Use Collections.sort(List) to sort a List)

2. Arrays (Use Arrays.sort(array) to sort an array, like int[])

An example which uses this feature to solve a problem is as follows,

https://open.kattis.com/problems/nothanksopen.kattis.com

Basically, we can create an array using ArrayList and then pass that array as the argument of the Collections.sort(), after that the array will be sorted ascending order, according to the natural order of its elements.

public class nothanks {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    sc.nextLine();
    ArrayList<Integer> card = new ArrayList<>();
    for (int i = 0; i < n; i += 1) {
      card.add(sc.nextInt());
    }
    Collections.sort(card);
    int ans = card.get(0);
    for (int i = 1; i < n; i += 1) {
      if (card.get(i - 1) + 1 != card.get(i)) {
        ans += card.get(i);
      }
    }
    System.out.println(ans);
  }
}