Number of Inversions in Array
Measures how close an array is to being sorted by counting pairs where i < j and arr[i] > arr[j].
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Asked in interviews at
Reference implementation (Python)
def count_inversions(arr):
inv_count = 0
for i in range(len(arr)):
for j in range(i+1, len(arr)):
if arr[i] > arr[j]: inv_count += 1
return inv_countEmbed this visualization
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<iframe src="/embed/count-inversions" width="100%" height="380" style="border:1px solid #e6e8ec;border-radius:14px" loading="lazy" title="3D algorithm visualization by CodeWithMunnaX"></iframe>Frequently asked
What is the time and space complexity of Number of Inversions in Array?
Number of Inversions in Array runs in O(n log n) time and O(n) auxiliary space.
Is the Number of Inversions in Array visualizer free?
The core 3D visualizer, Web Audio chimes and step intuition are free. A one-time ₹49 Pro Pass unlocks advanced algorithms, large custom arrays, Battle Arena and reel export.
Which companies ask Number of Inversions in Array in interviews?
Number of Inversions in Array shows up in interviews at Google, Amazon, Netflix.
How does the 3D visualization of Number of Inversions in Array work?
Each array value becomes a 3D pillar whose height maps to its value. Comparisons glow amber, swaps flash red, and settled elements lock green while a floating pointer badge tracks the active index — synchronized line-by-line with the Python code.