feat: double linked list

1 files changed, 172 insertions, 0 deletions

diff --git a/I_anno/Programmazione_2/data_structures/list_double.cc b/I_anno/Programmazione_2/data_structures/list_double.cc
new file mode 100644
index 0000000..b229237
--- /dev/null
+++ b/I_anno/Programmazione_2/data_structures/list_double.cc
@@ -0,0 +1,172 @@
+#include<iostream>
+
+using namespace std;
+
+template<typename T>
+struct node {
+    T value;
+    node* prev;
+    node* next;
+};
+
+
+template<typename T>
+class list {
+public:
+    list() : _head{nullptr} {}
+
+    ~list() {
+        while(_head != nullptr) {
+            node<T>* tmp = _head->next;
+            delete tmp;
+            _head = tmp;
+        }
+    }
+
+    list* push_front(T val) {
+        if(_head == nullptr) {
+            _head = new node<T>{val, nullptr, nullptr};
+        } else {
+            _head = new node<T>{val, nullptr, _head};
+            _head->next->prev = _head;
+        }
+
+        return this;
+    }
+
+    list* push_back(T val) {
+        node<T>* iter = _head;
+        if(_head == nullptr) {
+            _head = new node<T>{val, nullptr, nullptr};
+        } else {
+            while(iter->next != nullptr) {
+                iter = iter->next;
+            }
+            iter->next = new node<T>{val, iter, nullptr};
+        }
+
+        return this;
+    }
+
+    list* push_after_value(T val, T newval) {
+        node<T>* iter = _head;
+        while(iter && iter->value != val)
+            iter = iter->next;
+
+        if(iter == nullptr)
+            return this->push_front(newval);
+
+        node<T>* nod = new node<T>{newval, iter, iter->next};
+        iter->next = nod;
+        nod->next->prev = nod;
+
+        return this;
+    }
+
+    list* push_before_value(T val, T newval) {
+        node<T>* iter = _head;
+
+        if(iter->value == val)
+            return this->push_front(newval);
+
+        while(iter && iter->next && iter->next->value != val)
+            iter = iter->next;
+
+        if(iter == nullptr)
+            return this->push_front(newval);
+
+        node<T>* nod = new node<T>{newval, iter, iter->next};
+        iter->next = nod;
+        nod->next->prev = nod;
+
+        return this;
+    }
+
+    list* pop_front() {
+        if(_head == nullptr)
+            return this;
+
+        node<T>* elem = _head;
+        _head = _head->next;
+        _head->prev = nullptr;
+        delete elem;
+
+        return this;
+    }
+
+    list* pop_back() {
+        if(_head == nullptr)
+            return this;
+
+        node<T>* iter = _head;
+
+        while(iter->next && iter->next->next) {
+            iter = iter->next;
+        }
+
+        if(iter->next == nullptr) {
+            delete iter;
+            _head = nullptr;
+        } else if(iter->next->next) {
+            delete iter->next->next;
+        } else {
+            delete iter->next;
+        }
+
+        iter->next = nullptr;
+
+        return this;
+    }
+
+    void print() {
+        node<T>* iter = _head;
+        while(iter != nullptr) {
+            cout << iter->value << ' ';
+            cout << "[[ " << (iter->prev!=nullptr ? iter->prev->value : -1) << ", ";
+            cout << (iter->next!=nullptr ? iter->next->value : -1) << " ]],  ";
+            iter = iter->next;
+        }
+    }
+private:
+    node<T>* _head;
+};
+
+int main() {
+    list<int>* l = new list<int>{};
+    l->push_front(2)->push_front(1);
+    l->print(); cout << endl;
+    l->push_back(5);
+    l->print(); cout << endl;
+    l->push_back(10)->push_back(15);
+    l->print(); cout << endl;
+    l->push_after_value(5, 6);
+    l->print(); cout << endl;
+    l->push_after_value(5, 7);
+    l->print(); cout << endl;
+    l->push_before_value(5, 4);
+    l->print(); cout << endl;
+    l->push_before_value(5, 3);
+    l->print(); cout << endl;
+    l->pop_back();
+    l->print(); cout << endl;
+    l->pop_front();
+    l->print(); cout << endl;
+    l->pop_back();
+    l->print(); cout << endl;
+
+    // output
+    /*
+     * 1 [[ -1, 2 ]],  2 [[ 1, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 5 ]],  5 [[ 2, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 5 ]],  5 [[ 2, 10 ]],  10 [[ 5, 15 ]],  15 [[ 10, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 5 ]],  5 [[ 2, 6 ]],  6 [[ 5, 10 ]],  10 [[ 6, 15 ]],  15 [[ 10, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 5 ]],  5 [[ 2, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, 10 ]],  10 [[ 6, 15 ]],  15 [[ 10, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 4 ]],  4 [[ 2, 5 ]],  5 [[ 4, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, 10 ]],  10 [[ 6, 15 ]],  15 [[ 10, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 4 ]],  4 [[ 2, 3 ]],  3 [[ 4, 5 ]],  5 [[ 3, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, 10 ]],  10 [[ 6, 15 ]],  15 [[ 10, -1 ]],
+     * 1 [[ -1, 2 ]],  2 [[ 1, 4 ]],  4 [[ 2, 3 ]],  3 [[ 4, 5 ]],  5 [[ 3, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, 10 ]],  10 [[ 6, -1 ]],
+     * 2 [[ -1, 4 ]],  4 [[ 2, 3 ]],  3 [[ 4, 5 ]],  5 [[ 3, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, 10 ]],  10 [[ 6, -1 ]],
+     * 2 [[ -1, 4 ]],  4 [[ 2, 3 ]],  3 [[ 4, 5 ]],  5 [[ 3, 7 ]],  7 [[ 5, 6 ]],  6 [[ 7, -1 ]],
+     */
+
+    return 0;
+}