Strings and tries interview questions

Quick facts

Recall the answer first, then tap Show to check.

• Strings are immutableShowHide

  Python str objects never change; s += t builds a new string, so a loop of n appends can cost O(n²).

• str.joinShowHide

  "".join(parts) computes the total length once and copies each part once: O(total length).

• str.startswith with a tupleShowHide

  s.startswith(("http://", "https://")) tests several prefixes in one call.

• str.find and inShowHide

  text.find(p) returns the first index or -1; CPython uses a fast search that is usually linear in practice.

• Kotlin StringBuilderShowHide

  In Kotlin, build strings in loops with buildString { append(...) } or a StringBuilder.