Variable-length keyword arguments (**kwargs) in Python - Time & Space Complexity

Time Complexity: Variable-length keyword arguments (**kwargs)

O(n)

Understanding Time Complexity

When using variable-length keyword arguments, the program handles an unknown number of named inputs.

We want to know how the time to process these inputs changes as more keywords are added.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

def print_keys(**kwargs):
    for key in kwargs:
        print(key)

print_keys(a=1, b=2, c=3)

This function prints all the keys passed as keyword arguments.

Identify Repeating Operations

• Primary operation: Looping over all keys in the keyword arguments.
• How many times: Once for each key passed in kwargs.

How Execution Grows With Input

As the number of keyword arguments grows, the loop runs more times, so the work grows steadily.

Input Size (n)	Approx. Operations
10	10 print operations
100	100 print operations
1000	1000 print operations

Pattern observation: The work increases directly with the number of keyword arguments.

Final Time Complexity

Time Complexity: O(n)

This means the time to run grows in a straight line with the number of keyword arguments.

Common Mistake

[X] Wrong: "Using **kwargs makes the function run instantly no matter how many arguments."

[OK] Correct: The function still needs to look at each keyword to process it, so more keywords mean more work.

Interview Connect

Understanding how variable keyword arguments affect time helps you explain function behavior clearly and shows you can think about code efficiency.

Self-Check

"What if the function also processed the values of kwargs inside the loop? How would the time complexity change?"