第一题数独计数

考虑dfs遍历所有情况

n = int(input())

def check(grid, x, y, v):
    dx = [1, 0, -1, 0]
    dy = [0, 1, 0, -1]
    for i in range(4):
        nx, ny = x + dx[i], y + dy[i]
        if 0 <= nx < 3 and 0 <= ny < 3:
            if grid[nx][ny] == 0:
                continue
            if abs(grid[nx][ny] - v) == 1:
                return False
    return True

def dfs(grid, vst, i):
    if i > 9:
        return 1
    if i in vst:
        return dfs(grid, vst, i+1)

    count = 0

    for x in range(3):
        for y in range(3):
            if (grid[x][y]==0 and check(grid, x, y, i)):
                grid[x][y] = i
                count += dfs(grid, vs