Card Flipping Game
The given problem can be solved by using the following approach:
Identify Bad Numbers: First, we’ll identify the numbers that cannot be considered as good numbers. These are the numbers that are printed on both the front and back of the same card.
Find the Minimum Good Number: Next, we’ll look for the smallest number that is not among the bad numbers and that appears on the back of some card. If we find such a number, we’ll return it.
No Good Number: If no good number is found, we’ll return 0.
Python solution:


Explanation:
 We use a set comprehension to identify all the bad numbers (numbers printed on both sides of the same card).
 We then iterate through both
fronts
andbacks
arrays to find the minimum number that is not in thebad_numbers
set.  If we find a good number, we return it. Otherwise, we return 0.
The time complexity of this code is (O(n)), where (n) is the length of the fronts
or backs
array.