If a mistake is later detected, then we must backtrack to the point of error and try another alternative. This is called backup 如果以后发现它是错误的，我们必须退回到点，再试另外的选择。这种方法称为回溯。收藏
At other times,one may find it necessary to backtrack to a previous Step． 在另一些场合,可能有必要重复前一步骤。收藏
动词解释：