Sort Target
Algorithm
Speed
Normal ~12s · 35 ms ×3
ShiftSort(2017)
▶ Try this Source
O(n log n) ✓ Stable ✗ In-place
🔧 How it works

Scans the input to detect both ascending and descending runs, reverses any descending runs in-place to convert them to ascending, then merges all runs using an adaptive strategy similar to Timsort.

🎯 Key property

Symmetric run detection, recognising both forward and backward sequences, doubles the chance of finding a long natural run at any position, making it especially effective on inputs that mix ascending and descending sections.

👁 Watch for
  • Compare adjacent pairs are tested to distinguish ascending runs from descending ones; descending run boundaries are recorded for reversal
  • Swap detected descending runs are reversed in-place by swapping symmetric pairs around the midpoint, converting them to ascending at zero allocation cost
  • RangeCopy after all runs are prepared, adjacent runs are merged using a buffer-based merge step identical to Timsort's
🕰 History 🌳 Lineage ⚡ Optimization
UsesRun DetectionSortedness DetectionCopy-Smaller Strategy
Initial State
This is the array before sorting. Follow ShiftSort step by step.
Main Array
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RunsDetect 0 runs on stack
Waiting for run detection…
0 / 1,026 ops ( 0.0%) 0.0%
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