Given an array A of positive integers, call a (contiguous, not necessarily distinct) subarray of A good if the number of different integers in that subarray is exactly K.
(For example, [1,2,3,1,2] has 3 different integers: 1, 2, and 3.)
Return the number of good subarrays of A.
 
Example 1:
Input: A = [1,2,1,2,3], K = 2
Output: 7
Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2].

Example 2:
Input: A = [1,2,1,3,4], K = 3
Output: 3
Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].

 
Note:

1 <= A.length <= 20000
1 <= A[i] <= A.length
1 <= K <= A.length

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'class Solution:\n    def subarraysWithKDistinct(self, A: List[int], K: int) -> int:\n        # seems like you need 3 pointers, shink from either side\n        ans, ctr, lb, count = 0, {}, 0, 0\n        for i, val in enumerate(A): \n            if val not in ctr: \n                ctr[val] = 0\n            ctr[val] += 1\n            \n            # try to code it up first    \n            while len(ctr) > K:\n                ctr[A[lb]] -= 1\n                if ctr[A[lb]] == 0: \n                    del ctr[A[lb]]\n                lb += 1\n    \n            if len(ctr) == K: \n                p2, count, ctr1 = lb, 0, collections.Counter()\n                while len(ctr) == K:\n                    count += 1\n                    ctr[A[p2]] -=1\n                    if ctr[A[p2]] == 0:\n                        del ctr[A[p2]]\n                    ctr1[A[p2]] += 1\n                    p2 += 1\n                ans += count\n                for k, v in ctr1.items(): \n                    # recover step, kind of lame\n                    ctr[k] = ctr.get(k, 0) + v\n        return ans\n                \nclass Window:\n    def __init__(self):\n        self.count = collections.Counter()\n        self.nonzero = 0\n\n    def add(self, x):\n        self.count[x] += 1\n        if self.count[x] == 1:\n            self.nonzero += 1\n\n    def remove(self, x):\n        self.count[x] -= 1\n        if self.count[x] == 0:\n            self.nonzero -= 1\n\nclass Solution(object):\n    def subarraysWithKDistinct(self, A, K):\n        window1 = Window()\n        window2 = Window()\n        ans = left1 = left2 = 0\n\n        for right, x in enumerate(A):\n            window1.add(x)\n            window2.add(x)\n\n            while window1.nonzero > K:\n                window1.remove(A[left1])\n                left1 += 1\n\n            while window2.nonzero >= K:\n                window2.remove(A[left2])\n                left2 += 1\n\n            ans += left2 - left1\n\n        return ans'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'subarraysWithKDistinct'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 7884