From 70d3573b9af6bdff64f261141ad87648a63f9404 Mon Sep 17 00:00:00 2001
From: Dmitri Naumov <github@naumov.de>
Date: Wed, 23 May 2018 13:29:38 +0200
Subject: [PATCH] [BL] Generalize quick sort to input iterators.
---
BaseLib/quicksort.h | 48 ++++++++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 20 deletions(-)
diff --git a/BaseLib/quicksort.h b/BaseLib/quicksort.h
index eb3da1c9096..2bfb66e377a 100644
--- a/BaseLib/quicksort.h
+++ b/BaseLib/quicksort.h
@@ -20,37 +20,45 @@
namespace BaseLib
{
-/// @pre {end<=array.size() and perm.size()==array.size()}
-template <typename T1, typename T2 = std::size_t>
-void quicksort(T1* array, std::size_t beg, std::size_t end, T2* perm)
+/// @pre {first1 <= last1 and the second iterator can be incremented
+/// distance(first1, last1) times}
+template <typename It1, typename It2>
+void quicksort(It1 first1, It1 last1, It2 first2)
{
- assert (beg <= end);
+ using T1 = typename std::iterator_traits<It1>::value_type;
+ using T2 = typename std::iterator_traits<It2>::value_type;
- // Zip input arrays.
std::vector<std::pair<T1, T2>> data;
- data.reserve(end-beg);
- std::transform(array+beg, array+end, perm+beg,
- std::back_inserter(data),
- [](T1 const& t1, T2 const& t2)
- {
- return std::make_pair(t1, t2);
- });
+ data.reserve(std::distance(first1, last1));
+ std::transform(
+ first1, last1, first2, std::back_inserter(data),
+ [](T1 const& t1, T2 const& t2) { return std::make_pair(t1, t2); });
// Sort data using first element of the pair.
- std::sort(data.begin(), data.end(),
- [](std::pair<T1, T2> const& a, std::pair<T1, T2> const& b)
- {
- return (a.first < b.first);
- });
+ std::sort(begin(data), end(data),
+ [](std::pair<T1, T2> const& a, std::pair<T1, T2> const& b) {
+ return (a.first < b.first);
+ });
// Unzip sorted data.
- for (std::size_t i = 0; i < data.size(); i++)
+ for (auto const& pair : data)
{
- array[beg+i] = data[i].first;
- perm[beg+i] = data[i].second;
+ *first1 = pair.first;
+ *first2 = pair.second;
+ ++first1;
+ ++first2;
}
}
+/// @pre {end<=array.size() and perm.size()==array.size()}
+template <typename T1, typename T2 = std::size_t>
+void quicksort(T1* array, std::size_t beg, std::size_t end, T2* perm)
+{
+ assert(beg <= end);
+
+ quicksort(array + beg, array + end, perm + beg);
+}
+
template <typename T1, typename T2 = std::size_t>
void quicksort(std::vector<T1>& array, std::size_t beg, std::size_t end, std::vector<T2>& perm)
{
--
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