> For the complete documentation index, see [llms.txt](https://851958789.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://851958789.gitbook.io/notes/0892_surface_area_of_3d_shapes/slt.md).

# 思路1

For each tower, its surface area is 4 *v + 2 However, 2 adjacent tower will hide the area of connected part. The hidden part is min(v1, v2) and we need just minus this area* 2

Time Complexity: O(N^2)