Problem: 2062C - Cirno and Operations
Language: java

Solution 1 (runtime: 218 ms):
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Olynpiade3 {
    static FastScanner scan = new FastScanner(new InputStreamReader(System.in));
    public static void main(String[] args) {
        int t = scan.nextInt();
        for (int i = 0; i < t; i++)
            solve();
    }
    static void solve(){
        int n = scan.nextInt();
        long[] posl = new long[n];
        posl[0] = scan.nextInt();
        int pos;
        long sum1 = 0, sum2 = 0, max = posl[0];
        for (int i = 1; i < n; i++){
            posl[i] = scan.nextInt();
            max += posl[i];
            sum1 += posl[i] - posl[i-1];
            sum2 += posl[i-1] - posl[i];
        }
        //System.out.println(Arrays.toString(posl) + " " + sum1 + " " + sum2 + " " + max);
        int znak;
        long sum;
        for (int i = 0; i < n - 1; i++){
            pos = 1;
            if (sum1 > sum2){
                znak = 1;
            }else
                znak = -1;
            posl[0] = (long) znak * (posl[1] - posl[0]);
            sum1 = 0; sum2 = 0; sum = posl[0];
            if (n - 1 >= 2)
                while (pos != n - i - 1){
                    pos++;
                    posl[pos - 1] = (long) znak * (posl[pos] - posl[pos-1]);
                    sum += posl[pos - 1];
                    sum1 += posl[pos - 1] - posl[pos - 2];
                    sum2 += posl[pos - 2] - posl[pos - 1];
                    //System.out.println(Arrays.toString(posl));
                }

            if (sum > max)
                max = sum;
            //System.out.println(Arrays.toString(posl));
        }
        System.out.println(max);
    }
}


class FastScanner

{

    private BufferedReader br;

    private StringTokenizer st;



    public FastScanner(InputStreamReader reader)

    {

        br = new BufferedReader(reader);

    }



    public String next()

    {

        while (st == null || !st.hasMoreTokens())

        {

            try

            {

                st = new StringTokenizer(br.readLine());

            } catch (Exception e)

            {

                e.printStackTrace();

            }

        }

        return st.nextToken();

    }



    public int nextInt()

    {

        return Integer.parseInt(next());

    }



    public double nextDouble()

    {

        return Double.parseDouble(next());

    }



    public void close() throws Exception

    {

        br.close();

    }

}

Solution 2 (runtime: 249 ms):
import java.util.*;
import java.io.*;
import java.math.*;

public class sub {

	// can i get expert by summer please

	static int mod = 998244353;

	public static void main(String args[]) throws IOException {
		int t = sc.nextInt();
		while (t-- > 0) {
			int n = sc.nextInt();
			ArrayList<Long> a = new ArrayList();
			if (n == 1) {
				out.println(sc.nextInt());
			} else {
				long ans = 0;
				for (int i = 0; i < n; i++) {
					a.add(sc.nextLong());
					ans+=a.get(i);
				}
				for (int i = 1; i < n; i++) {
					ArrayList<Long> copy = new ArrayList();
					for(int j = 0;j<a.size()-1;j++) {
						copy.add(a.get(j) - a.get(j + 1));
					}
					a=copy;
					long sum = 0;
					for (int j = 0; j < a.size(); j++) {
						sum += a.get(j);
					}
					if(sum<0) {
						Collections.reverse(a);
					}
					
					ans=Math.max(ans,Math.abs(sum));
				}
				out.println(ans);
			}
		}
		out.close();
	}

//	static long bincoef(int n, int k) {
//	    if (n < k) return 0L;
//	    return (p[n] * pow((p[n - k] * p[k]) % mod, mod - 2, mod)) % mod;
//	}

	static long pow(long a, long b, long mod) {
		if (b == 0) {
			return 1L;
		}
		long val = pow(a, b / 2, mod);
		if (b % 2 == 0) {
			return val * val % mod;
		}
		return val * val % mod * a % mod;
	}

	static long gcd(long a, long b) {
		if (b == 0) {
			return a;
		}
		return gcd(b, a % b);
	}

	static long lcm(long a, long b) {
		return a * b / gcd(a, b);
	}

	static Kattio sc = new Kattio();
	static PrintWriter out = new PrintWriter(System.out);

	static class Kattio {

		static BufferedReader r;
		static StringTokenizer st;

		public Kattio() {
			r = new BufferedReader(new InputStreamReader(System.in));
		}

		public String next() {
			try {
				while (st == null || !st.hasMoreTokens()) {
					st = new StringTokenizer(r.readLine());
				}
				return st.nextToken();
			} catch (Exception e) {
				return null;
			}
		}

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

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

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