Get Maximum Amount
There are n types of items in a shop, where the number of items of type i is denoted by quantity[i]. The price of the items is determined dynamically, where the price of the ith item is equal to the remaining number of items of type i. There are m customers in line to buy the items from the shop, and each customer will buy exactly one item of any type.
The shopkeeper, being greedy, tries to sell the items in a way that maximises revenue. Find the maximum amount the shopkeeper can earn by selling exactly m items to the customers optimally.
Complete the function getMaximumAmount in the editor.
getMaximumAmount has the following parameter:
int quantity[n]: the number of items of each type
Returns
long integer: the maximum revenue possible
1Example 1
2Example 2

Constraints
Limits and guarantees your solution can rely on.
1 ≤ n ≤ 10^51 ≤ m ≤ 10^51 ≤ quantity[i] ≤ 10^5