Python Coding Challange - Question with Answer (01040925)

 

Let’s break it down step by step 👇

Code:

from collections import defaultdict
d = defaultdict(int)
d['a'] += 1
print(d['b'])

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Explanation:

1. defaultdict(int)

   • Creates a dictionary-like object.

   • When you try to access a key that doesn’t exist, it automatically creates it with a default value.

   • Here, the default value is given by int(), which returns 0.

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2. d['a'] += 1

   • Since 'a' is not yet in the dictionary, defaultdict creates it with 0 as the default.

   • Then, 0 + 1 = 1.

   • Now, d = {'a': 1}.

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3. print(d['b'])

   • 'b' doesn’t exist in the dictionary.

   • defaultdict automatically creates it with default value int() → 0.

   • So, it prints 0.

   • Now, d = {'a': 1, 'b': 0}.

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Final Output:

0

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⚡ Key Point: Unlike a normal dict, accessing a missing key in defaultdict does not raise a KeyError. Instead, it inserts the key with a default value.

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