From fa670eac6d73cbc9196603dd285d2240ef89f735 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <dcariotti24@gmail.com>
Date: Fri, 8 May 2020 19:58:21 +0200
Subject: feat: circulat list

---
 .../data_structures/circle_list.cc                 | 162 +++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 I_anno/Programmazione_2/data_structures/circle_list.cc

diff --git a/I_anno/Programmazione_2/data_structures/circle_list.cc b/I_anno/Programmazione_2/data_structures/circle_list.cc
new file mode 100644
index 0000000..ee32a8c
--- /dev/null
+++ b/I_anno/Programmazione_2/data_structures/circle_list.cc
@@ -0,0 +1,162 @@
+#include<iostream>
+
+using namespace std;
+
+template<typename T>
+struct node {
+    T value;
+    node* next;
+};
+
+
+template<typename T>
+class list {
+public:
+    list() : _head{nullptr} {}
+
+    ~list() {
+        while(_head != nullptr) {
+            node<T>* tmp = _head->next;
+            delete tmp;
+            _head = tmp;
+        }
+    }
+
+    node<T>* last_element() {
+        node<T>* iter = _head;
+        while(iter && iter->next != _head) {
+            iter = iter->next;
+        }
+
+        return iter;
+    }
+
+    list* push_front(T val) {
+        auto elem = last_element();
+        _head = new node<T>{val, _head};
+        if(elem == nullptr)
+            elem = _head;
+
+        elem->next = _head;
+
+        return this;
+    }
+
+    list* push_back(T val) {
+        node<T>* iter = _head;
+        if(_head == nullptr) {
+            _head = new node<T>{val, _head};
+        } else {
+            while(iter->next != nullptr && iter->next != _head) {
+                iter = iter->next;
+            }
+            iter->next = new node<T>{val, _head};
+        }
+        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);
+
+        iter->next = new node<T>{newval, iter->next};
+
+        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);
+
+        iter->next = new node<T>{newval, iter->next};
+
+        return this;
+    }
+
+    list* pop_front() {
+        if(_head == nullptr)
+            return this;
+
+        auto last_e = last_element();
+
+        if(last_e == _head) {
+            delete _head;
+            _head = nullptr;
+        } else {
+            node<T>* elem = _head;
+            _head = _head->next;
+            last_e->next = _head;
+            delete elem;
+        }
+
+        return this;
+    }
+
+    list* pop_back() {
+        if(_head == nullptr)
+            return this;
+
+        node<T>* iter = _head;
+        auto last_e = last_element();
+
+        if(last_e == _head) {
+            delete iter;
+            _head = nullptr;
+        } else {
+            while(iter->next != last_e) {
+                iter = iter->next;
+            }
+
+            delete iter->next;
+            iter->next = _head;
+        }
+
+        return this;
+    }
+
+    void print() {
+        node<T>* iter = _head;
+        while(iter) {
+            cout << iter->value << ' ';
+            iter = iter->next;
+            if(iter == _head) break;
+        }
+    }
+private:
+    node<T>* _head;
+};
+
+int main() {
+    list<int>* l = new list<int>{};
+    l->push_back(4);
+    l->push_back(1);
+    l->push_back(0);
+    l->push_front(2);
+    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;
+    l->push_front(3);
+    l->print(); cout << endl;
+    l->push_after_value(4, 7);
+    l->print(); cout << endl;
+    l->push_before_value(3, 5);
+    l->print(); cout << endl;
+
+    return 0;
+}
-- 
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