Provide an example of algorithm with time complexity of O(c^k)?

O(ck) – exponential time complexity algorithms are, for example, brute-force search and traveling salesman problems.

An example may be if you had a set of characters of length c, and have the password of length k. Then you would need a O(ck) time to break the password, like O(10n) is trying to break a password by testing every possible combination (assuming numerical password of length n).