# 求まったとき if cell == 81: print(*arr, sep="\n") exit()
i, j = cell//9, cell%9 if arr[i][j] == 0:
# 順に代入する for n inrange(1, 10):
# --- 行 --- if n in arr[i]: continue
# --- 列 --- is_in_col = False for r inrange(9): is_in_col |= arr[r][j] == n if is_in_col: continue
# --- ブロック --- is_in_block = False for r inrange(i//3*3, i//3*3+3): for c inrange(j//3*3, j//3*3+3): is_in_block |= arr[r][c] == n if is_in_block: continue