Python Coding challenge - Day 463| What is the output of the following Python Code?

 

Code Explanation:

Importing defaultdict:

from collections import defaultdict

You import defaultdict from the collections module.

defaultdict is like a regular dictionary but provides a default value if the key has not been set yet.

Creating a defaultdict with int:

d = defaultdict(int)

int is the default factory function. It returns 0 when a new key is accessed.

So, d['missing_key'] will return 0 instead of raising a KeyError.

Updating the dictionary:

d['a'] += 1

d['a'] is not in the dictionary, so defaultdict uses int() to assign it 0.

Then 0 + 1 = 1 → d['a'] = 1

d['b'] += 2

Similarly, d['b'] = 0 + 2 = 2

Accessing a non-existent key:

print(d['a'], d['b'], d['c'])

d['a'] → 1

d['b'] → 2

d['c'] is not set, so it gets the default value of 0 (via int())

Final Output:

1 2 0