From fd96b451521e1b229d1dfdf9348faecd2be9d753 Mon Sep 17 00:00:00 2001
From: Jonathan Poelen <jonathan.poelen@gmail.com>
Date: Sat, 8 Nov 2025 22:27:00 +0100
Subject: [PATCH] optimize mp_nth_element

compiler | gcc-15 | clang-20
before   | 0:00.66s - 206316K | 0:01.77s - 246832K
after    | 0:00.63s - 192944K | 0:01.76s - 245956K

```cpp
template<class I> using test = mp_nth_element<mp_iota_c<I::value+1>, I, mp_less>;

using r1 = mp_transform<test, mp_iota_c<30>>;
```
---
 include/boost/mp11/algorithm.hpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/boost/mp11/algorithm.hpp b/include/boost/mp11/algorithm.hpp
index 948aacd..d4d6f56 100644
--- a/include/boost/mp11/algorithm.hpp
+++ b/include/boost/mp11/algorithm.hpp
@@ -679,9 +679,7 @@ template<template<class...> class L, class T1, class... T, std::size_t I, templa
 {
     static_assert( I < 1 + sizeof...(T), "mp_nth_element index out of range" );
 
-    template<class U> using F = P<U, T1>;
-
-    using part = mp_partition<L<T...>, F>;
+    using part = mp_partition_q<L<T...>, mp_sort_impl_f<T1, P>>;
 
     using L1 = mp_first<part>;
     static std::size_t const N1 = mp_size<L1>::value;