Stages.java

/**
 * https://codeforces.com/problemset/problem/1011/A #greedy #sorting #implementation two way: sort
 * the character array. or use arr[26] to store characters.
 */
import java.util.Arrays;
import java.util.Scanner;

public class Stages {

  static int calMinimalWeigth() {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int k = sc.nextInt();
    char[] arr = new char[n];
    String s = sc.next();
    arr = s.toCharArray();
    Arrays.sort(arr);

    int sum = (arr[0] - 'a' + 1);
    if (k == 1) {
      return sum;
    }
    int count = 1;
    int result = -1;
    int prevIdx = 0;
    for (int i = 1; i < n; i++) {
      if (arr[i] != arr[prevIdx] && arr[i] != (arr[prevIdx] + 1)) {
        count += 1;
        sum += (arr[i] - 'a' + 1);
        prevIdx = i;
      }
      if (count == k) {
        result = sum;
        break;
      }
    }

    return result;
  }

  public static void main(String[] args) {
    System.out.println(calMinimalWeigth());
  }
}