refactor(arrays, subarrays): add doctests and edge cae

Author: BrianLusina

datastructures/arrays/subarrays_with_fixed_bounds/README.md

@@ -12,7 +12,7 @@ A subarray in nums is called a fixed-bound subarray if it satisfies the followin
 Constraints:
 
 - 2 ≤ nums.length ≤ 10^3
-- 1 ≤ nums[i], minK, maxK ≤10^3
+- 1 ≤ nums[i], minK, maxK ≤ 10^3
 
 ## Examples
 

datastructures/arrays/subarrays_with_fixed_bounds/__init__.py

@@ -3,7 +3,8 @@
 
 def count_subarrays(nums: List[int], min_k: int, max_k: int) -> int:
     """
-    Counts the number of subarrays in the provided array which satisfies the following conditions:
+    This counts the number of subarrays in the provided array which satisfies the following conditions:
+
     1. The smallest value in the subarray equals min_k.
     2. The largest value in the subarray equals max_k.
 
@@ -14,7 +15,21 @@ def count_subarrays(nums: List[int], min_k: int, max_k: int) -> int:
 
     Returns:
         int: The number of subarrays that satisfies the conditions.
+
+    Examples:
+        >>> count_subarrays([2,1,4,3,2],2,3)
+        1
+        >>> count_subarrays([1,2,3,2,1],1,3)
+        5
+        >>> count_subarrays([4,4,4],4,4)
+        6
+        >>> count_subarrays([2,2,2],4,4)
+        0
     """
+    # edge case to handle empty arrays or invalid bounds
+    if not nums or min_k > max_k:
+        return 0
+
     last_min, last_max, last_invalid = -1, -1, -1
     count = 0
 
@@ -28,4 +43,4 @@ def count_subarrays(nums: List[int], min_k: int, max_k: int) -> int:
 
         count += max(0, min(last_min, last_max) - last_invalid)
 
-    return count
+    return count