Add Trapping Rain Water solution in arrays

Author: leo-soumyajit

data_structures/arrays/trapping_rain_water.py

@@ -0,0 +1,20 @@
+def trap(height):
+    if not height:
+        return 0
+    left, right = 0, len(height) - 1
+    max_left, max_right = 0, 0
+    water = 0
+    while left < right:
+        if height[left] < height[right]:
+            if height[left] >= max_left:
+                max_left = height[left]
+            else:
+                water += max_left - height[left]
+            left += 1
+        else:
+            if height[right] >= max_right:
+                max_right = height[right]
+            else:
+                water += max_right - height[right]
+            right -= 1
+    return water