Count Number of Teams Python Solution

lcpy gen -n 1395   # by problem number
lcpy gen -s count_number_of_teams   # by problem name

Input: rating = [2,5,3,4,1]
Output: 3
Explanation: We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1).

Input: rating = [2,1,3]
Output: 0
Explanation: We can't form any team given the conditions.

Input: rating = [1,2,3,4]
Output: 4

class Solution:
    # Time: O(n^2)
    # Space: O(1)
    def num_teams(self, rating: list[int]) -> int:
        n = len(rating)
        total = 0
        for mid in range(n):
            less_before = sum(rating[i] < rating[mid] for i in range(mid))
            greater_before = mid - less_before
            less_after = sum(rating[k] < rating[mid] for k in range(mid + 1, n))
            greater_after = n - mid - 1 - less_after
            total += less_before * greater_after + greater_before * less_after
        return total