Question: Given an integer array nums, return true if any value appears more than once in the array, otherwise return false.

How to Solve: We can create a secondary list that we can start to throw the values from our array nums into, and check to see if they already exist in the list or not. As soon as we enter a number that already exists in our list, it will return True and end. If it goes through the entire nums array without breaking, our list has no duplicates, and we can return False.

Answer:

def hasDuplicate(nums: List[int]) -> bool:
        num_list = []
        for num in nums:
            if num not in num_list:
                num_list.append(num)
            else:
                return True
        return False