URI1697JaidaAndMultiplyGame.java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;

/**
 * See
 * <a href="https://www.urionlinejudge.com.br/judge/en/problems/view/1697">Jaida
 * and Multiply Game</a>
 *
 * @author Brian Yeicol Restrepo Tangarife
 */
public class URI1697JaidaAndMultiplyGame {

    static Reader in = new Reader(System.in);
    static Writer out = new Writer(System.out);
    static final int MAX = 2000000;

    public static void main(String[] args) throws IOException {
        int T = in.nextInt(), N;
        int a;
        boolean[] m;
        while (T-- > 0) {
            N = in.nextInt();
            m = new boolean[MAX];
            for (int i = 0; i < N; i++) {
                a = in.nextInt();
                if (a < MAX) {
                    m[a] = true;
                }
            }
            if (!m[1]) {
                out.println(0);
            } else {
                for (int i = 2; i < MAX; i++) {
                    if (!m[i]) {
                        out.println(i - 1);
                        break;
                    }
                    for (int j = i * 2; j < MAX; j += i) {
                        m[j] = true;
                    }
                }
            }
        }
        in.close();
        out.flush();
        out.close();
    }

    ////////////////////////////////////////////////////////////////////////////
    /////////////////////////////  INPUT / OUTPUT  /////////////////////////////
    ////////////////////////////////////////////////////////////////////////////
    static class Reader implements Closeable {

        private final BufferedReader reader;
        private StringTokenizer tokenizer;

        public Reader(InputStream input) {
            reader = new BufferedReader(
                    new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        private StringTokenizer getTokenizer() throws IOException {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                String line = nextLine();
                if (line == null) {
                    return null;
                }
                tokenizer = new StringTokenizer(line);
            }
            return tokenizer;
        }

        public boolean hasNext() throws IOException {
            return getTokenizer() != null;
        }

        public String next() throws IOException {
            return hasNext() ? tokenizer.nextToken() : null;
        }

        public String nextLine() throws IOException {
            tokenizer = null;
            return reader.readLine();
        }

        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        public float nextFloat() throws IOException {
            return Float.parseFloat(next());
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public String[] nextStringArray(int size) throws IOException {
            String[] array = new String[size];
            for (int i = 0; i < size; i++) {
                array[i] = next();
            }
            return array;
        }

        public int[] nextIntArray(int size) throws IOException {
            int[] array = new int[size];
            for (int i = 0; i < size; i++) {
                array[i] = nextInt();
            }
            return array;
        }

        public long[] nextLongArray(int size) throws IOException {
            long[] array = new long[size];
            for (int i = 0; i < size; i++) {
                array[i] = nextLong();
            }
            return array;
        }

        public double[] nextDoubleArray(int size) throws IOException {
            double[] array = new double[size];
            for (int i = 0; i < size; i++) {
                array[i] = nextDouble();
            }
            return array;
        }

        @Override
        public void close() throws IOException {
            tokenizer = null;
            reader.close();
        }
    }

    static class Writer implements Closeable, Flushable {

        private final PrintWriter writer;

        public Writer(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(objects[i]);
            }
        }

        public void println(Object... objects) {
            print(objects);
            writer.println();
        }

        @Override
        public void close() {
            writer.close();
        }

        @Override
        public void flush() {
            writer.flush();
        }
    }
}