Final edits

Author: cclauss

Diff for: dynamic_programming/trapped_water.py

@@ -1,8 +1,8 @@
 """
-Given an array of non-negative integers representing an elevation map where
-the width of each bar is 1,this program calculates how much rainwater can be trapped.
+Given an array of non-negative integers representing an elevation map where the width
+of each bar is 1, this program calculates how much rainwater can be trapped.
 
-Example - height = [0,1,0,2,1,0,1,3,2,1,2,1]
+Example - height = (0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1)
 Output: 6
 This problem can be solved using the concept of "DYNAMIC PROGRAMMING".
 
@@ -13,46 +13,48 @@
 """
 
 
-def trapped_rainwater(height: list[int]) -> int:
+def trapped_rainwater(heights: tuple[int]) -> int:
     """
-    The trapped_rainwater function calculates the total amount of rainwater
-    that can be trapped given an array of bar heights.
-    It uses a dynamic programming approach, determining the maximum height of bars
-    on both sides for each bar, and then computing the trapped water above each bar.
+    The trapped_rainwater function calculates the total amount of rainwater that can be
+    trapped given an array of bar heights.
+    It uses a dynamic programming approach, determining the maximum height of bars on
+    both sides for each bar, and then computing the trapped water above each bar.
     The function returns the total trapped water.
 
-    >>> trapped_rainwater([0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1])
+    >>> trapped_rainwater((0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1))
     6
-    >>> trapped_rainwater([7, 1, 5, 3, 6, 4])
+    >>> trapped_rainwater((7, 1, 5, 3, 6, 4))
     9
+    >>> trapped_rainwater((7, 1, 5, 3, 6, -1))
+    Traceback (most recent call last):
+        ...
+    ValueError: No height can be negative
     """
-    if not height:
+    if not heights:
         return 0
-    if any(h < 0 for h in height):
+    if any(h < 0 for h in heights):
         raise ValueError("No height can be negative")
-    length = len(height)
+    length = len(heights)
 
     left_max = [0] * length
-    left_max[0] = height[0]
-    for i in range(1, length):
-        left_max[i] = max(height[i], left_max[i - 1])
+    left_max[0] = heights[0]
+    for i, height in enumerate(heights[1:], start=1):
+        left_max[i] = max(height, left_max[i - 1])
 
     right_max = [0] * length
-    right_max[length - 1] = height[length - 1]
+    right_max[-1] = heights[-1]
     for i in range(length - 2, -1, -1):
-        right_max[i] = max(height[i], right_max[i + 1])
+        right_max[i] = max(heights[i], right_max[i + 1])
 
-    trapped_water: int = 0
-
-    for i in range(length):
-        water_level = min(left_max[i], right_max[i])
-        trapped_water += water_level - height[i]
-
-    return trapped_water
+    return sum(
+        min(left, right) - height
+        for left, right, height in zip(left_max, right_max, heights)
+    )
 
 
 if __name__ == "__main__":
     import doctest
 
     doctest.testmod()
-    print(f"{trapped_rainwater([0,1,0,2,1,0,1,3,2,1,2,1])}")
+    print(f"{trapped_rainwater((0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1)) = }")
+    print(f"{trapped_rainwater((7, 1, 5, 3, 6, 4)) = }")