883. Projection area of 3D Shapes

On a n * n grid, we place some 1 * 1 * 1 cubes is axis-aligned with the X, y, and Z axes.

Each value V = grid[i][j] Represents a tower of v cubes placed on top of the grid cell (I, J).

Now we view the projection of these cubes onto the XY, YZ, and ZX planes.

A projection is a shadow, which maps our 3 dimensional figure to a 2 dimensional plane.

Here, we is viewing the "shadow" when looking at the cubes from the top, the front, and the side.

Return The total area of all three projections.

Example 1:

Input: [[2]]
Output:5

Example 2:

Input: [[1,2],[3,4]]
Output:17
Explanation:
Here is the three projections ("shadows") of the shape made with each axis-aligned plane.

Example 3:

Input: [[1,0],[0,2]]
Output:8

Example 4:

Input: [[1,1,1],[1,0,1],[1,1,1]]
Output:14

Example 5:

Input: [[2,2,2],[2,1,2],[2,2,2]]
Output:21

Note:

• 1 <= grid.length = grid[0].length <= 50
• 0 <= Grid[i][j] <= 50

class Solution:    def projectionArea(self, grid):        """        :type grid: List[List[int]]        :rtype: int        """        front = [0] * len(grid)        side = [0] * len(grid)        top = 0        for i in range(len(grid)):            for j in range(len(grid[i])):                if grid[i][j] == 0:                    continue                top += 1                front[i] = max(front[i],grid[i][j])                side[j] = max(side[j],grid[i][j])        return top + sum(front) + sum(side)

883. Projection area of 3D Shapes