compiles now I think and seems to work but haven't tested extensively

Map.hpp

@@ -4,11 +4,9 @@
 #include <cassert>
 #include <cstddef>
 #include <initializer_list>
-#include <iterator>
-#include <list>
-#include <optional>
 #include <stdexcept>
 #include <utility>
+#include <vector>
 
 // everything is super interconnected so some forward declarations are needed at
 // various points
@@ -32,11 +30,12 @@ Direction operator!(Direction dir) {
 }
 template <typename Key_T, typename Mapped_T> struct BookKeeping {
   using Self = BookKeeping<Key_T, Mapped_T>;
-  using ValueType = std::pair<const Key_T, Mapped_T>;
+  using ValueType = std::pair<Key_T, Mapped_T>;
+  using Ptr = typename std::vector<Self>::iterator;
   friend class Map<Key_T, Mapped_T>;
   Map<Key_T, Mapped_T> &container;
   ValueType value;
-  typename std::list<Self>::iterator self;
+  Ptr self;
   Color color;
   // nullptr indicates empty
   Self *parent;
@@ -45,6 +44,26 @@ template <typename Key_T, typename Mapped_T> struct BookKeeping {
   Self *prev;
   Self *next;
   BookKeeping(Map<Key_T, Mapped_T> &container) : container{container} {}
+  BookKeeping(BookKeeping const &rhs)
+      : container{rhs.container}, value{rhs.value}, self{rhs.self},
+        color{rhs.color}, parent{rhs.parent}, left{rhs.left}, right{rhs.right},
+        prev{rhs.prev}, next{rhs.next} {}
+  // if pointing to different containers throws
+  BookKeeping &operator=(BookKeeping const &rhs) {
+    if (&this->container != &rhs.container) {
+      throw std::invalid_argument{"can only reassign Bookkeeping "
+                                  "values/iterators from the same map object"};
+    }
+    this->value = rhs.value;
+    this->self = rhs.self;
+    this->color = rhs.color;
+    this->parent = rhs.parent;
+    this->left = rhs.left;
+    this->right = rhs.right;
+    this->prev = rhs.prev;
+    this->next = rhs.next;
+    return *this;
+  }
   // reference to a pointer because the alternatives were worse
   inline Self *&child(Direction dir) {
     switch (dir) {
@@ -54,6 +73,8 @@ template <typename Key_T, typename Mapped_T> struct BookKeeping {
     case Direction::Right:
       return right;
       break;
+    default:
+      assert(false);
     }
   }
   // this is root/P for this method
@@ -87,7 +108,7 @@ template <typename Key_T, typename Mapped_T> struct BookKeeping {
         G->left = S;
       }
     } else {
-      T->root = S;
+      T.root = S;
     }
   }
 };
@@ -95,7 +116,7 @@ template <typename Key_T, typename Mapped_T> struct BookKeeping {
 // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree
 template <typename Key_T, typename Mapped_T> class Map {
 private:
-  using ValueType = std::pair<const Key_T, Mapped_T>;
+  using ValueType = std::pair<Key_T, Mapped_T>;
   using Node = BookKeeping<Key_T, Mapped_T>;
   using Map_T = Map<Key_T, Mapped_T>;
 
@@ -259,7 +280,7 @@ private:
   Node *root;
   Node *min;
   Node *max;
-  std::list<Node> nodes;
+  std::vector<Node> nodes;
 
 public:
   Map() : root{nullptr}, min{nullptr}, max{nullptr}, nodes{} {}
@@ -295,7 +316,11 @@ public:
     // it here
     auto [parent, dir] = this->locate_slot(key);
     if (parent == nullptr) {
-      return this->end();
+      if (this->root->value.first == key) {
+        return Iterator{root};
+      } else {
+        return this->end();
+      }
     }
     if (parent->child(dir) == nullptr) {
       return this->end();
@@ -449,13 +474,14 @@ public:
   // an iterator pointing to the element with the same key, and false.
   std::pair<Iterator, bool> insert(const ValueType &val) {
     auto [parent, dir] = locate_slot(val.first);
-    bool ret = parent->child(dir) == nullptr;
+    bool ret = parent == nullptr || parent->child(dir) == nullptr;
     if (!ret) {
       return std::make_pair(Iterator{parent->child(dir)}, ret);
     }
     Node to_insert{*this};
     to_insert.value = val;
     this->nodes.push_back(std::move(to_insert));
+    this->nodes.back().self = (--this->nodes.end());
     insert_helper(&nodes.back(), parent, dir);
 
     if (min == nullptr || val.first < min->value.first) {
@@ -465,7 +491,7 @@ public:
       max = &nodes.back();
     }
 
-    return std::make_pair(Iterator{&nodes.back()}, ret);
+    return std::make_pair(Iterator(&nodes.back()), ret);
   }
   template <typename IT_T> void insert(IT_T range_beg, IT_T range_end) {
     std::for_each(range_beg, range_end,
@@ -562,7 +588,6 @@ private:
 public:
   // TODO: check that the way of reconnecting next and prev works
   void erase(Iterator pos) {
-    auto &container = pos.ref->container;
     // simple cases
     Node *ref = pos.ref;
     // 2 children
@@ -593,15 +618,13 @@ public:
     // no children and root
     else if (ref->left == nullptr && ref->right == nullptr) {
       this->root = nullptr;
-      this->nodes.erase(ref->value);
     }
     // no children and red
-    else if (ref->left == nodes.end() && ref->right == nodes.end()) {
+    else if (ref->left == nullptr && ref->right == nullptr) {
       Node *next = ref->next;
       Node *prev = ref->prev;
       prev->next = next;
       next->prev = prev;
-      this->nodes.erase(ref->value);
     }
     // complicated case of black node with no kids
     else {