题解与来源题共享。已有题解默认通过；新增或编辑后需由来源域管理员审核。待审核、驳回题解仅作者和审核管理员可见。来源域：system

• 0

  Jaylin LV 7 @ 2026-3-12 14:30:37

  import sys
  input = lambda:sys.stdin.readline().strip()
  
  s = input()
  k = int(input())
  n = len(s)
  left = 0
  from collections import defaultdict
  count = defaultdict(int)
  res = 0
      
  for right in range(n):
      count[s[right]] += 1
      while count[s[right]] > k:
          count[s[left]] -= 1
          left += 1   
      res += (right - left + 1)
  print(res)