Get Max Reward Points

Problem Overview

• Given rewards for n items, find the maximum total points by choosing a purchase order where each buy reduces all remaining rewards by 1 (not below 0), and each item can be bought once.
• Input: int array reward[n] (0 ≤ reward[i] ≤ 1e6, 1 ≤ n ≤ 1e5); Output: long_int maximum reward points.
• Context: Amazon shopping offers with diminishing rewards after each purchase.
• From Amazon interviews: a coding interview problem and common interview question.