Zip for combining sequences in Swift - Time & Space Complexity

Time Complexity: Zip for combining sequences

O(n)

Understanding Time Complexity

When we combine two lists using zip, we want to know how the work grows as the lists get bigger.

How does the time to combine change when the input lists grow?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

let numbers = [1, 2, 3, 4, 5]
let letters = ["a", "b", "c", "d", "e"]

for pair in zip(numbers, letters) {
    print(pair)
}
    

This code pairs elements from two lists and prints each pair.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: Looping through pairs created by zip.
• How many times: Once for each element up to the smaller list's length.

How Execution Grows With Input

As the lists get longer, the loop runs more times, matching the smaller list size.

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

Pattern observation: The work grows directly with the number of pairs zipped.

Final Time Complexity

Time Complexity: O(n)

This means the time to combine grows in a straight line with the size of the smaller list.

Common Mistake

[X] Wrong: "Zip runs in constant time because it just pairs elements."

[OK] Correct: Zip must look at each element to pair them, so time grows with list size.

Interview Connect

Understanding how zip scales helps you explain how combining data works efficiently in real tasks.

Self-Check

"What if the two lists have very different sizes? How would that affect the time complexity?"