Big-O Cheatsheet
Quick reference for Time & Space Complexities.
Data Structures
| Data Structure | Avg Access | Avg Search | Avg Insert | Avg Delete | Worst Space |
|---|---|---|---|---|---|
| Array | O(1) | O(n) | O(n) | O(n) | O(n) |
| Stack | O(n) | O(n) | O(1) | O(1) | O(n) |
| Queue | O(n) | O(n) | O(1) | O(1) | O(n) |
| Singly-Linked List | O(n) | O(n) | O(1) | O(1) | O(n) |
| Hash Table | N/A | O(1) | O(1) | O(1) | O(n) |
| Binary Search Tree | O(log n) | O(log n) | O(log n) | O(log n) | O(n) |
| AVL Tree | O(log n) | O(log n) | O(log n) | O(log n) | O(n) |
Sorting Algorithms
| Algorithm | Best Time | Average Time | Worst Time | Worst Space |
|---|---|---|---|---|
| Quicksort | O(n log n) | O(n log n) | O(n²) | O(log n) |
| Mergesort | O(n log n) | O(n log n) | O(n log n) | O(n) |
| Heapsort | O(n log n) | O(n log n) | O(n log n) | O(1) |
| Bubble Sort | O(n) | O(n²) | O(n²) | O(1) |
| Insertion Sort | O(n) | O(n²) | O(n²) | O(1) |
| Selection Sort | O(n²) | O(n²) | O(n²) | O(1) |