Python Coding challenge - Day 822| What is the output of the following Python Code?

 

Code Explanation:

1) Importing defaultdict from the collections module

from collections import defaultdict

The collections module provides specialized container datatypes beyond Python’s built-in dict, list, etc.

defaultdict is a subclass of dict that automatically assigns a default value to a new key that doesn’t yet exist.

You don’t have to check if a key is already present before using it.

2) Creating a defaultdict that uses int as the default factory

d = defaultdict(int)

Here, int is passed as the default factory function.

Calling int() without arguments returns 0.

This means that if you access a key that doesn’t exist, it is automatically created with a default value of 0.

So, d behaves like a normal dictionary, but every new key starts at 0 instead of raising a KeyError.

3) Looping through a list of numbers

for x in [1, 2, 2, 3, 3, 3]:

    d[x] += 1

This loop iterates through the list [1, 2, 2, 3, 3, 3].

For each value of x, the line d[x] += 1 increments the count for that number.

Step-by-step execution:

x = 1: key 1 doesn’t exist → d[1] becomes 0 + 1 = 1.

x = 2: key 2 doesn’t exist → d[2] becomes 0 + 1 = 1.

Next x = 2: key 2 exists → d[2] becomes 1 + 1 = 2.

x = 3: key 3 doesn’t exist → d[3] becomes 0 + 1 = 1.

Next x = 3: d[3] becomes 1 + 1 = 2.

Next x = 3: d[3] becomes 2 + 1 = 3.

After the loop, d contains:

{1: 1, 2: 2, 3: 3}

4) Printing the sum of counts for keys 2 and 3

print(d[2] + d[3])

Accesses the values for keys 2 and 3 in the dictionary.

d[2] is 2 (since 2 appeared twice).

d[3] is 3 (since 3 appeared three times).

Adds them: 2 + 3 = 5.

The print() statement outputs this result.

Final Output

5

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