Problem: 2062C - Cirno and Operations
Language: java

Solution 1 (runtime: 312 ms):
// package main;
import java.util.Scanner;
import java.io.PrintWriter;
import java.util.List;
import java.util.ArrayList;


// 100 * 50

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);

        int t = scanner.nextInt();
        for (int i = 0; i < t; i++) {
            int n = scanner.nextInt();
            List<Long> ar = new ArrayList<>();

            for (int j = 0; j < n; j++) {
                ar.add(scanner.nextLong());
            }

            long res = sum(ar);

            while (ar.size() > 1) {
                res = Math.max(res, sum(ar));

                List<Long> newAr = new ArrayList<>();
                for (int j = 1; j < ar.size(); j++) {
                    newAr.add(ar.get(j) - ar.get(j - 1));
                }
                res = Math.max(res, Math.abs(sum(newAr)));
                ar = newAr;
            }
            out.println(res);
        }
        out.flush();
        out.close();
        scanner.close();
    }

    private static long sum(List<Long> ar) {
        long sum = 0;
        for (long a : ar) {
            sum += a;
        }
        return sum;
    }
}


Solution 2 (runtime: 155 ms):
import java.io.*;
import java.util.*;

public class Code {

    // Input and Output
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter out = new PrintWriter(System.out);

    // For parsing integers, longs, and strings efficiently
    static StringTokenizer st;

    // Entry point
    public static void main(String[] args) throws IOException {
        int t; // Number of test cases
        t = nextInt(); // Uncomment this line if multiple test cases
        while (t-- > 0) {
            solve(); // Call the solve function for each test case
        }
        out.close(); // Close the output stream
    }

    // Solve function for each test case

    static void solve() throws IOException {
        int n = nextInt();
        long[] arr = new long[n];

        for(int i=0;i<n;i++){
            arr[i] = nextLong();
        }

        int now = n;
        long ans = Long.MIN_VALUE;

        for(int i=0;i<n;i++) {
            long sum = 0L;
            for (int j = 0; j < now; j++) {
                sum += arr[j];
            }

            if(i==0){
                ans = Math.max(ans, sum);
            }
            else{
                ans = Math.max(ans, Math.abs(sum));
            }

            for(int j = 0;j<now-1;j++){
                arr[j] = arr[j+1] - arr[j];
            }
            now--;
        }

        out.println(ans);
    }

    // Utility methods for faster input
    static String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }

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

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

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

    char nextChar() {
        try {
            return (char) br.read();
        } catch (IOException e) {
            e.printStackTrace();
            return '\0'; // Return null character in case of an error
        }
    }

    static String nextLine() throws IOException {
        return br.readLine();
    }

    // Utility functions
    static int gcd(int a, int b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

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

    static boolean isPrime(int n) {
        if (n <= 1) return false;
        if (n <= 3) return true;
        if (n % 2 == 0 || n % 3 == 0) return false;
        for (int i = 5; i * i <= n; i += 6) {
            if (n % i == 0 || n % (i + 2) == 0) return false;
        }
        return true;
    }

    static long power(long x, long y, long p) {
        long res = 1;
        x = x % p;
        while (y > 0) {
            if ((y & 1) == 1)
                res = (res * x) % p;
            y = y >> 1;
            x = (x * x) % p;
        }
        return res;
    }

    public static void sort(int[] arr)
    {
        //because Arrays.sort() uses quicksort which is dumb
        //Collections.sort() uses merge sort
        ArrayList<Integer> ls = new ArrayList<Integer>();
        for(int x: arr)
            ls.add(x);
        Collections.sort(ls);
        for(int i=0; i < arr.length; i++)
            arr[i] = ls.get(i);
    }
}