This solution applying array differences; Instead of storing the actual values in the array, you store the difference between the current element and the previous element.

ArrayManipulation.java

private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        String[] nm = scanner.nextLine().split(" ");

        int n = Integer.parseInt(nm[0]);

        int m = Integer.parseInt(nm[1]);

        int[][] queries = new int[m][3];

        for (int i = 0; i < m; i++) {
            String[] queriesRowItems = scanner.nextLine().split(" ");
            scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

            for (int j = 0; j < 3; j++) {
                int queriesItem = Integer.parseInt(queriesRowItems[j]);
                queries[i][j] = queriesItem;
            }
        }

        long result = arrayManipulation(n, queries);

        System.out.println(result);
        scanner.close();
    }

    static long arrayManipulation(int n, int[][] queries) {
        long max = 0;
        long[] arrayOperations = new long[n];

        int j = 0;
        for (int[] query : queries) {
            int left = query[j];
            int right = query[j + 1];
            int operator = query[j + 2];
            arrayOperations[left - 1] += operator;
            if (right < n) arrayOperations[right] -= operator;
        }
        long temp = 0;
        for (int i = 0; i < n; i++) {
            temp += arrayOperations[i];
            if (max < temp)
                max = temp;
        }
        return max;
    }

You can check the problem description here