Strings
1. Overview
Strings are used for storing text. A string variable contains a collection of characters surrounded by double quotes. Strings are written in between " ".
Strings are immutable (unchangeable) objects.
In Python, you can’t add a new character at the end of a string, instead you have to create a new string, copy the elements of the original string and append the character to the end of the new string. This will take O(n).
- Use Cases:
- Example: Efficient searching and sorting (e.g., database indexing).
- Example: Suitable for priority-based tasks (e.g., heaps for priority queues).
2. Operations and Complexities
| Operation | Time Complexity | Notes |
|---|---|---|
| Search | O(n) | Linear search, i.e., you have to go through all the elements of the strin |
| Insertion | O(…) | Special cases (e.g., balanced or unbalanced) |
| Deletion | O(…) |
Indexing is constant time.
5. Must-Know Problems
7. Cheat Sheet / Key Formulas
- Check if a character is in a string:
if 'f' in s:
Sprint(True)