Interview question

What is the difference between a Python list, dictionary, and set in terms of use case? Use case के हिसाब से Python list, dictionary, और set में क्या अंतर है?

Answer

Structure	Ordered?	Duplicates?	Access by	Best for
list	Yes	Allowed	Index	Ordered sequences, need duplicates
dict	Yes (insertion, Python 3.7+)	Keys unique, values can repeat	Key	Key-value lookups
set	No	Not allowed (auto-dedupes)	Membership only	Uniqueness, fast membership tests

# List - ordered, allows duplicates
tags = ['python', 'web', 'python']
print(tags)  # ['python', 'web', 'python']

# Dict - key-value pairs
user = {'name': 'John', 'age': 30}
print(user['name'])  # John

# Set - unique values, fast membership check
unique_tags = set(tags)
print(unique_tags)  # {'python', 'web'}
print('python' in unique_tags)  # O(1) average - much faster than list 'in'

# Choosing based on need
visited_ids = set()  # fast duplicate checking
for user_id in [1, 2, 1, 3]:
    if user_id not in visited_ids:
        visited_ids.add(user_id)
        print(f'Processing {user_id}')

Structure	Ordered?	Duplicates?	Access	सबसे अच्छा
list	हाँ	Allowed	Index	Ordered sequences
dict	हाँ (insertion order)	Keys unique	Key	Key-value lookups
set	नहीं	Allowed नहीं	सिर्फ membership	Uniqueness, fast checks

tags = ['python', 'web', 'python']
print(tags)  # duplicates रहती हैं

user = {'name': 'John', 'age': 30}
print(user['name'])  # John

unique_tags = set(tags)
print(unique_tags)  # {'python', 'web'}
print('python' in unique_tags)  # तेज़ O(1)

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