Compilation Order

Statement

There are a total of $n$ classes labeled with the English alphabet ($A$, $B$, $C$, and so on). Some classes are dependent on other classes for compilation. For example, if class $B$ extends class $A$, then $B$ has a dependency on $A$. Therefore, $A$ must be compiled before $B$.

Given a list of the dependency pairs, find the order in which the classes should be compiled.

Constraints:

• Class name should be an uppercase character.
• $0 \leq$ dependencies.length $\leq 676$
• dependencies[i].length $= 2$
• All dependency pairs should be unique.

Examples

In the above examples, the arrows represent the relationship between these classes. For example, the arrow $A \rightarrow C$ shows that $C$ extends $A$, and therefore, $C$ is dependent on $A$.

Understand the problem

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Figure it out!

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Try it yourself

Implement your solution in main.go in the following coding playground. We have provided some useful code templates in the other file that you may build on to solve this problem.