Valid Anagram
Decide whether two strings are anagrams of each other.
Progress cannot be saved in this browser, so completed lessons will reset when you leave.
Lesson notes
Try it before you watch
Restate the problem in your own words, list the edge cases, and sketch a solution with its running time. Then play the video and compare.
Reveal the key idea
Compare the character counts of the two strings, for example with a Counter or a 26-slot array.
Pattern: Arrays & hashing. Trade memory for speed: sets and dictionaries answer 'have I seen this?' in O(1).
Complexity
| Measure | Bound |
|---|---|
| Time | O(n) |
| Extra space | O(1) for a fixed alphabet |
Walkthroughs often start from a simpler approach first; aim to reach these bounds. New to Big-O? Read understanding algorithmic complexity.