Resolved 'Subarrays with K Different Integers' LeetCode problem with an optimized solution

Author: DevOgabek

Python/subarrays_with_k_different_integers.py

@@ -0,0 +1,25 @@
+# Subarrays with K Different Integers
+
+class Solution:
+    def subarraysWithKDistinct(self, nums, k):
+        return self.subarraysWithAtMostKDistinct(nums, k) - self.subarraysWithAtMostKDistinct(nums, k - 1)
+
+    def subarraysWithAtMostKDistinct(self, nums, k):
+        ans = 0
+        count = [0] * (len(nums) + 1)
+
+        l = 0
+        for r in range(len(nums)):
+            count[nums[r]] += 1
+            if count[nums[r]] == 1:
+                k -= 1
+            while k == -1:
+                count[nums[l]] -= 1
+                if count[nums[l]] == 0:
+                    k += 1
+                l += 1
+            ans += r - l + 1
+        return ans
+    
+solution = Solution()
+print(solution.subarraysWithAtMostKDistinct([1,2,1,2,3], 2))