orlp/pdqsort

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2504 stars · 99 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Pattern-defeating quicksort (pdqsort) is a C++ sorting algorithm library that combines quicksort's fast average case with heapsort's fast worst case, achieving linear time on certain input patterns. It is a drop-in replacement for std::sort, available as a header-only library under the zlib license.

Use cases

• sort arrays faster than std::sort
• replace std::sort with a faster drop-in sorting algorithm
• sort data with many duplicate elements efficiently
• sort nearly-sorted or patterned input in linear time
• use a deterministic unstable sort with n log n worst case
• speed up sorting of arithmetic types with branchless comparisons

When to choose

• you need a faster replacement for std::sort in C++
• your data often contains patterns like ascending/descending runs or many equal elements
• you want a guaranteed n log n worst case without heapsort's overhead
• you want a small header-only library with no dependencies

When to avoid

• you need a stable sort
• you are not programming in C++
• you need parallel or external sorting for data larger than memory
• your comparison function is expensive and pattern detection overhead dominates

Facets

library · maturity stable

math developer-tools performance developer-tools cpp cross-platform sorting quicksort header-only drop-in-replacement introsort algorithms

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