import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Scanner;

public class Task_1263 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        String str = in.nextLine();
        int candidateCount = Integer.valueOf(str.substring(0, 1));
        int votersCount = Integer.valueOf(str.substring(2));
        int[] votersForCandidates = new int[candidateCount];
        double[] votersPercents = new double[candidateCount];
        int voter;
        for (int i = 0; i < votersCount; i++) {
            voter = Integer.valueOf(in.nextLine());
            votersForCandidates[voter - 1]++;
        }
        for (int i = 0; i < candidateCount; i++) {

            votersPercents[i] = new BigDecimal((double) 100 * votersForCandidates[i] / votersCount).setScale(2, RoundingMode.HALF_UP).doubleValue();
        }
        for (int i = 0; i < candidateCount; i++) {
            out.printf("%.2f%%%n", votersPercents[i]);
        }
        out.flush();
    }
}

Because of the Memory limit: which no more than 64 MB.

votersPercents array is useless and should be removed.
But the main error is you reading candidateCount in the wrong way. str.substring(0, 1) - how many digits can you read? What max candidateCount is?

You use Scanner class. It has method nextInt() - you can just use it, you don't need to read strings and split them into numbers manually.