Create trapping_rain_water.py

trapping_rain_water.py

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+def trap(height):
+    # Edge case: if the input array is empty, return 0
+    if not height:
+        return 0
+
+    # Initialize two pointers
+    left, right = 0, len(height) - 1
+    # Initialize variables to store the maximum heights on both sides
+    left_max, right_max = height[left], height[right]
+    # Initialize a variable to store the total water trapped
+    water_trapped = 0
+
+    # Loop until the two pointers meet
+    while left < right:
+        # If the left_max is less than the right_max, move the left pointer inward
+        if left_max < right_max:
+            left += 1
+            # Update the left_max value
+            left_max = max(left_max, height[left])
+            # Calculate the water trapped at the current position and add it to the total
+            water_trapped += left_max - height[left]
+        # If the right_max is less than or equal to the left_max, move the right pointer inward
+        else:
+            right -= 1
+            # Update the right_max value
+            right_max = max(right_max, height[right])
+            # Calculate the water trapped at the current position and add it to the total
+            water_trapped += right_max - height[right]
+
+    # Return the total water trapped
+    return water_trapped
+
+# Test Cases
+print(trap([4, 2, 0, 3, 2, 5]))  # Output: 9
+print(trap([1, 0, 2]))           # Output: 1