On a N * N grid, we place some 1 * 1 * 1 cubes.
Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j).
Return the total surface area of the resulting shapes.
Example 1:
Input: [[2]] Output: 10 Example 2:
Input: [[1,2],[3,4]] Output: 34 Example 3:
Input: [[1,0],[0,2]] Output: 16 Example 4:
Input: [[1,1,1],[1,0,1],[1,1,1]] Output: 32 Example 5:
Input: [[2,2,2],[2,1,2],[2,2,2]] Output: 46
Note:
1 <= N <= 50 0 <= grid[i][j] <= 50
public class Solution {
public int SurfaceArea(int[][] grid) {
int res = 0, n = grid.Length;
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
if (grid[i][j] > 0) res += grid[i][j] * 4 + 2;
if (i > 0) res -= Math.Min(grid[i][j], grid[i - 1][j]) * 2;
if (j > 0) res -= Math.Min(grid[i][j], grid[i][j - 1]) * 2;
}
}
return res;
}
}Time Complexity: O(n^2)
Space Complexity: O(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
