It is a good example of how lambda expressions can be used though. This solution enlarged my perspective.

Thanks for making my day man xD

Thanks for this great explanation

Random test cases are susceptible to cheating.

I have just taken off my hat...

How can the result be 9 for n=12 - the last sample test for java:

assertEquals(9, Solution.cardGame(12));

I find the result 8 on paper. Am I wrong??

This solution is not quite correct. I assume this passed the tests due to non-comprehensive test conditions. For instance consider the following case:

f(x=3, a=3, b=5, c=3) # This is the calling function

In the above case x must take the value "5" since its current value is "3" (Problem says: "You wish to assign to x the value other than its current one."), but the result of this solution is "3".

The reason is that dictionaries do not allow duplicate key words. When you do {a:b, b:c, c:a} for the above test values, the value of a (3 as keyword) will be 5, and when program see that c is the same with a (in terms of keyword), instead of creating a new key-value item, it will assign a again but this time with the value of 3.
So, the last dictionary will be {3:3, 5:3}, in which case the value "5" is unreachable which is the accual correct answer.

I hope it helps...
Stay safe :)