Arrays & Hashing pattern
Count Inversions
An inversion is a pair of indices i < j where arr[i] > arr[j], a measure of how far the array is from sorted. Count them all. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- 2 approaches
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Arrays & Hashing
From the first idea to the best one
- 01 Brute force · every pair O(n²)O(1) space
- 02 Optimized · count while merge sorting O(n log n)O(n) space
What you will learn
- How to read Count Inversions and spot the arrays & hashing pattern in it
- Brute force · every pair: O(n²) time, O(1) space
- Optimized · count while merge sorting: O(n log n) time, O(n) space
- The pseudocode for each approach, its line lit as the animation runs
- Practice: write your own pseudocode and get it checked
More Arrays & Hashing
See Count Inversions run, step by step
Sign in and this page opens on the animation, with all 13 Arrays & Hashing problems beside it.
DSA comes with the all labs plan and every ChaiCode batch.