Second Largest Number in Swift

Input: A = 7, B = 3, C = 9
Output: 7

Input: A = 12, B = 8, C = 3
Output: 8

There are three candidates to the solution: A, B and C. We should try out each of them until we find the correct one. How can we check if A is the solution? What should happen for A to be the second largest value?

A is the second largest value if min(B, C) <= A and A <= max(B, C). We can write an if statement checking these conditions and if they hold, return A:

if A >= min(B, C) and A <= max(B, C):
	return A

What if the conditions don't hold and A is not the solution? What should we do next?

We should test B. Similarly, B is the second largest value if min(A, C) <= B and B <= max(A, C). We can write an if statement checking these conditions and if they hold, return B.

if A >= min(B, C) and A <= max(B, C):
	return A
if B >= min(A, C) and B <= max(A, C):
	return B

What if not even B is the solution?

Then, it's clear that C is the solution, so we should return C. We don't even need to check the conditions anymore:

if A >= min(B, C) and A <= max(B, C):
	return A
if B >= min(A, C) and B <= max(A, C):
	return B
return C