Question

How to implement a function that check if there are duplicates in a list in Python

Answer 1

def has_duplicates(lst):
    for i in range(0, len(lst)):
        for j in range(i + 1, len(lst)):
            if lst[i] == lst[j]:
                return True
    return False


lst1 = ["python", "java", "python", "c", "c", "php", "c"]

print(has_duplicates(lst1))

lst2 = ["python", "java", "c", "php", "swift"]

print(has_duplicates(lst2))



'''
run:

True
False

'''

 

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Answer 2

def has_duplicates(lst):
    if len(lst) == len(set(lst)):
        return False
    else:
        return True


lst1 = ["python", "java", "python", "c", "c", "php", "c"]

print(has_duplicates(lst1))

lst2 = ["python", "java", "c", "php", "swift"]

print(has_duplicates(lst2))



'''
run:

True
False

'''

 

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Answer 3

def has_duplicates(lst):
    st = set()
    
    for element in lst:
        if element in st:
            return True
        else:
            st.add(element)   
            
    return False


lst1 = ["python", "java", "python", "c", "c", "php", "c"]

print(has_duplicates(lst1))

lst2 = ["python", "java", "c", "php", "swift"]

print(has_duplicates(lst2))



'''
run:

True
False

'''

 

70+ SQL courses for beginners and professionals