# A Contact List That's Fast to Search and Easy to Change: Binary Search Trees

Keep 100,000 contacts so a name is found on every keystroke, new contacts go in all day, and the screen shows everyone A to Z, or from Kai to Maya, without sorting: why an unsorted list, a sorted array and a dictionary each fall short, and the structure that fixes them, the binary search tree.

![Cheat sheet: A Contact List That's Fast to Search and Easy to Change: Binary Search Trees](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/5f2ca2efc42a4c8fafa7fbcd27f0ee95.webp)

- Category: Data Structures
- Level: Journeyman
- Tags: Binary Search Tree, Binary Tree, data structures, In-Order Traversal, Subtree
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/ds-binary-search-trees-cheat-sheet