LeetCode题解(0883)：三维形体投影面积(Python)

题目：原题链接（简单）

解法时间复杂度空间复杂度执行用时Ans 1 (Python)$O(N^2)$ : N为矩阵宽度$O(N)$ : N为矩阵宽度104ms (33.86%)Ans 2 (Python)$O(N^2)$ : N为矩阵宽度$O(1)$80ms (99.06%)Ans 3 (Python)

LeetCode的Python执行用时随缘，只要时间复杂度没有明显差异，执行用时一般都在同一个量级，仅作参考意义。

解法一（记录所有投影结果）：

def projectionArea(self, grid: List[List[int]]) -> int: size = len(grid) max_x = [0 for _ in range(size)] max_y = [0 for _ in range(size)] ans = 0 for i in range(size): for j in range(size): if grid[i][j] > 0: ans += 1 max_x[i] = max(max_x[i], grid[i][j]) max_y[j] = max(max_y[j], grid[i][j]) return ans + sum(max_x) + sum(max_y)

解法二（不记录投影结果）：

def projectionArea(self, grid): size = len(grid) ans = 0 for i in range(size): max_x = 0 max_y = 0 for j in range(size): if grid[i][j]: ans += 1 max_x = max(max_x, grid[i][j]) max_y = max(max_y, grid[j][i]) ans += max_x + max_y return ans