secondMax.py

def secondMax(nums):
        
        """
        :type num: List[string]
        
        """
        if len(nums) == 0:
            return -1
            
        fmax = float('-inf')
        for i in range(0,len(nums)):
            if fmax < int(nums[i]):
                fmax = int(nums[i])
        smax = float('-inf')        
        for i in range(0,len(nums)):
            if int(nums[i]) < fmax and smax < int(nums[i]):
                smax = int(nums[i])
        
        if smax == float('-inf'):
           return -1
    
        return smax
        

#Example usage 
print(secondMax(['1','1','2','3','4']*3000))


#Assertions
def assertc(actual, expect):
    assert actual, expect

assert secondMax(['1','1','2','3','4']*3000),3
assert secondMax(["1","2","3"]),2
assert secondMax(["3", "-2"]),-2
assert secondMax(["4", "4", "4"]),-1
assert secondMax([]),-1