892. Surface area of 3D Shapes

Problem

NxN lattice, stacked with 1x1x1 cubes, grid[i][j] represents the number of cubes stacked on a coordinate grid, seeking the surface area of this 3D polygon.

Input: [[1,2],[3,4]]
Output:34

Ideas

Just add up the surface area of each cylinder (GRID[I][J] * 4, 4 for four sides, 2 for upper and lower Two Faces), then subtract the overlapping parts.
The overlapping portion is the smaller grid value in the adjacent column in the X-direction (or y-direction).

Code

class Solution(object):    def surfaceArea(self, grid):        """        :type grid: List[List[int]]        :rtype: int        """        s = 0        n = len(grid)        for i in range(n):            for j in range(n):                if grid[i][j]:                     s += grid[i][j] * 4 + 2                if i:                    s -= min(grid[i][j], grid[i-1][j]) * 2                if j:                    s -= min(grid[i][j], grid[i][j-1]) * 2        return s

Similar topics

883. Projection area of 3D Shapes

892. Surface area of 3D Shapes