happybirthday

The difference between a topological and standard sort is shown in Listing 2 (you can download happybirthday. txt from Resources).

拓扑排序和标准sort之间的差别如清单2所示（您可以从参考资料下载happybirthday.txt）。

On a friend or colleague's birthday, a cheerful "Happy Birthday! " is enough.

在朋友或者同事的生日上，一句“HappyBirthday！”就足够了。