LeetCode题解(0840)：矩阵中的幻方数量(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)$O(W\times H)$ : W和H为矩阵的宽和高$O(1)$48ms (69.47%)Ans 2 (Python)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（暴力解法）：

def numMagicSquaresInside(self, grid: List[List[int]]) -> int: x = len(grid) y = len(grid[0]) if x < 3 or y < 3: return 0 ans = 0 for i in range(x - 2): for j in range(x - 2): # 检查是否仅包含1-9 num_list = {grid[i][j], grid[i][j + 1], grid[i][j + 2], grid[i + 1][j], grid[i + 1][j + 1], grid[i + 1][j + 2], grid[i + 2][j], grid[i + 2][j + 1], grid[i + 2][j + 2]} if not (1 in num_list and 2 in num_list and 3 in num_list and 4 in num_list and 5 in num_list and 6 in num_list and 7 in num_list and 8 in num_list and 9 in num_list): continue # 检查行列对角线加和是否正确（枚举8条线） num = grid[i][j] + grid[i + 1][j] + grid[i + 2][j] if grid[i][j + 1] + grid[i + 1][j + 1] + grid[i + 2][j + 1] != num: continue if grid[i][j + 2] + grid[i + 1][j + 2] + grid[i + 2][j + 2] != num: continue if grid[i][j] + grid[i][j + 1] + grid[i][j + 2] != num: continue if grid[i + 1][j] + grid[i + 1][j + 1] + grid[i + 1][j + 2] != num: continue if grid[i + 2][j] + grid[i + 2][j + 1] + grid[i + 2][j + 2] != num: continue if grid[i][j] + grid[i + 1][j + 1] + grid[i + 2][j + 2] != num: continue if grid[i + 2][j] + grid[i + 1][j + 1] + grid[i][j + 2] != num: continue ans += 1 return ans