var arr = [];
    var max = 0;
    // init each element of arr to 0
    for (let l = 0; l < n; l++) {
        arr[l] = 0;
    }
    // for each sum operation in queries
    for (let i = 0; i < queries.length; i++) {
       // update arr with number to add at index=queries[i][0]  and number to remove at index=queries[i][0]+1 => this will allow us to build each element of the final array by summing all elements before it. The aim of this trick is to lower time complexity
        arr[queries[i][0]-1] += queries[i][2];
        if (queries[i][1] < arr.length) {
            arr[queries[i][1]] -= queries[i][2];
        }
    }
    for (let j = 1; j < n; j++) {
        arr[j] += arr[j-1];
    }
    for (let k = 0; k < arr.length; k++) {
        max = Math.max(max, arr[k]);
    }
    //max = Math.max(...arr); // not working for big arrays
    return max;