「🏗️」 wip(ex02): algo is basically done now i think ? just need some optimisations iirc

ex02/PmergeMe.hpp

@@ -33,19 +33,22 @@ std::vector<size_t> generateJacobsthal(size_t n)
     return seq;
 }
 
-template <typename T>
-struct Pair {
-    T first;
-    T second;
-};
+template <typename Container, typename T>
+typename Container::iterator binaryInsertPosition(Container &c, const T &value)
+{
+    typename Container::iterator first = c.begin();
+    typename Container::iterator last = c.end();
 
-template <typename T>
-struct PairComp {
-    bool operator()(const Pair<T> &x, const Pair<T> &y) const
-	{
-        return x.second < y.second;
+    while (first < last)
+    {
+        typename Container::iterator mid = first + (last - first) / 2; //tzvetan told me a better way iirc but i don't remember D:
+        if (*mid < value)
+            first = mid + 1;
+        else
+            last = mid;
     }
-};
+    return first;
+}
 
 template <typename Container>
 Container fordJohnsonSort(const Container &input)
@@ -56,7 +59,7 @@ Container fordJohnsonSort(const Container &input)
     if (input.size() <= 1)
 		return input;
 
-    std::vector<Pair<T> > pairs;
+    std::vector<std::pair<T, T> > pairs;
     size_t i = 0;
     for (; i + 1 < input.size(); i += 2)
 	{
@@ -64,16 +67,16 @@ Container fordJohnsonSort(const Container &input)
         T b = input[i+1];
         if (a > b)
 			std::swap(a, b);
-        Pair<T> p;
-		p.first = a;
-		p.second = b;
-        pairs.push_back(p);
+
+        pairs.push_back(std::make_pair(a, b));
     }
 
-    std::sort(pairs.begin(), pairs.end(), PairComp<T>());
+	Container larger;
+	for (size_t j = 0; j < pairs.size(); ++j)
+		larger.push_back(pairs[j].second);
 
-    for (size_t k = 0; k < pairs.size(); ++k)
-        result.push_back(pairs[k].second);
+	larger = fordJohnsonSort(larger);
+	result = larger;
 
     std::vector<size_t> order = generateJacobsthal(pairs.size());
     std::vector<bool> inserted(pairs.size(), false);
@@ -83,8 +86,7 @@ Container fordJohnsonSort(const Container &input)
         size_t j = order[idx];
         if (j < pairs.size() && !inserted[j])
 		{
-            typename Container::iterator pos = std::lower_bound(
-                result.begin(), result.end(), pairs[j].first);
+            typename Container::iterator pos = binaryInsertPosition(result, pairs[j].first);
             result.insert(pos, pairs[j].first);
             inserted[j] = true;
         }
@@ -94,8 +96,7 @@ Container fordJohnsonSort(const Container &input)
 	{
         if (!inserted[j])
 		{
-            typename Container::iterator pos = std::lower_bound(
-                result.begin(), result.end(), pairs[j].first);
+            typename Container::iterator pos = binaryInsertPosition(result, pairs[j].first);
             result.insert(pos, pairs[j].first);
         }
     }
@@ -103,7 +104,7 @@ Container fordJohnsonSort(const Container &input)
     if (i < input.size())
 	{
         T leftover = input[i];
-        typename Container::iterator pos = std::lower_bound(result.begin(), result.end(), leftover);
+        typename Container::iterator pos = binaryInsertPosition(result, leftover);
         result.insert(pos, leftover);
     }