Multiline strings with trimIndent in Kotlin - Time & Space Complexity

Time Complexity: Multiline strings with trimIndent

O(n)

Understanding Time Complexity

We want to understand how the time to process multiline strings with trimIndent changes as the string size grows.

How does the trimming operation scale when the string has more lines?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

val text = """
    line one
    line two
    line three
""".trimIndent()

println(text)
    

This code creates a multiline string and removes common leading spaces from each line using trimIndent.

Identify Repeating Operations

• Primary operation: The function scans each line of the string to find the smallest indent and then removes that indent from all lines.
• How many times: It processes each line twice: once to find the indent, once to trim it.

How Execution Grows With Input

As the number of lines increases, the trimming work grows roughly in proportion to the number of lines.

Input Size (n lines)	Approx. Operations
10	About 20 line checks (2 per line)
100	About 200 line checks
1000	About 2000 line checks

Pattern observation: The work doubles if the number of lines doubles, showing a steady growth.

Final Time Complexity

Time Complexity: O(n)

This means the time to trim indentation grows linearly with the number of lines in the string.

Common Mistake

[X] Wrong: "trimIndent runs instantly no matter how big the string is."

[OK] Correct: The function must check each line to find and remove indentation, so more lines mean more work.

Interview Connect

Understanding how string operations scale helps you reason about performance in real apps, especially when handling large text data.

Self-Check

"What if we used trimMargin instead of trimIndent? How would the time complexity change?"