Find K maximum occurrences in unique K baskets until more than K distinct occurrences

k_distinct_occurences.py

from collections import Counter

def fruits_into_baskets(fruits):
  max_ctr = Counter()
  left_idx = 0
  distinct = 0
  max_k = 2
  ct = float('-inf')
  for right_idx, r_char in enumerate(fruits):
    if not max_ctr[r_char]:
      distinct += 1
    max_ctr[r_char] += 1
    while distinct > max_k:
      l_char = fruits[left_idx]
      if max_ctr[l_char]:
        max_ctr[l_char] -= 1
      if not max_ctr[l_char]:
        distinct -= 1
      left_idx += 1
    ct = max(ct, sum(v for _, v in max_ctr.most_common(2)))
  return ct