Python Coding challenge - Day 1271| What is the output of the following Python Code?

 

Code Explanation:

1. 📦 Import ChainMap

from collections import ChainMap

ChainMap comes from Python's collections module.

It allows multiple dictionaries to be treated as one combined mapping.

2. 🗂️ Create Dictionary a

a = {"x": 1}

Dictionary a contains:

x → 1

3. 🗂️ Create Dictionary b

b = {"x": 2, "y": 3}

Dictionary b contains:

x → 2

y → 3

Notice that both dictionaries have the key "x".

4. 🔗 Create the ChainMap

c = ChainMap(a, b)

Now c logically searches the mappings in this order:

c

 ↓

 a  →  {"x": 1}

 ↓

 b  →  {"x": 2, "y": 3}

The first mapping has priority.

So:

c["x"]

finds "x" in a first and returns 1.

5. ✏️ Update "x"

c["x"] = 10

This is the tricky part.

When assigning through a ChainMap, the assignment is made to the first mapping.

So:

a["x"] → 10

b["x"] → 2

b is not modified.

6. 🖨️ Print the Values

print(c["x"], a["x"], b["x"])

Now:

c["x"] → 10

a["x"] → 10

b["x"] → 2

Therefore:

10 10 2

🔄 Internal Flow

ChainMap(a, b)

      ↓

  Search/Update

      ↓

 First mapping = a

      ↓

a["x"] = 10

      ↓

b["x"] remains 2

✅ Final Output

10 10 2

100 Python Programs for Beginner with explanation