Implement Nth Largest Number

An Airtel Payments Bank analytics pipeline receives an unsorted array of integer transaction values. Implement a function that returns the nth largest value, counting duplicate values as separate elements.

You must avoid fully sorting the array. Use an appropriate data structure to maintain only the values needed to determine the result.

Formal Specification

Implement nth_largest(nums, n).

• Input: nums, a non-empty list of integers, and n, a 1-indexed integer.
• Output: The integer that would appear at position n when nums is sorted in descending order.
• Duplicate values count independently. For example, the second largest value in [7, 7, 3] is 7.