Leet Code

#3 Contains Duplicate

brian | Published: July 19, 2024, 6:01 p.m. | Updated: July 9, 2025, 10:15 p.m.

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'''
Problem:
Given an integer array nums, return true if any value appears 
at least twice in the array, and return false if every element is distinct.

 
'''


class Solution(object):
    def is_duplicate(self, nums:list):
        #first im creating an empty set
        numbers = set()
        #now we are going to loop over the list of numbers that will be passed in
        for number in nums:
            #next we check if the current number is in the set already
            #if it IS, then we return True
            if number in numbers:
                return True
            #if it is NOT, then we add that number to the set, and then continue  until we finish looping through
            #all the numbers, or until we find a duplicate
            else:
                numbers.add(number)
        #if the execution reaches up to this point, then that means we DID NOT find any duplicate and so we will return False
        return False
        


#the two is a duplicate, so it should return [True]
nums = [1, 2, 3, 4, 5]
solve = Solution()

print(solve.is_duplicate(nums))