feat: binary search tree

1 files changed, 225 insertions, 0 deletions

diff --git a/I_anno/Programmazione_2/data_structures/bst.cc b/I_anno/Programmazione_2/data_structures/bst.cc
new file mode 100644
index 0000000..9223e04
--- /dev/null
+++ b/I_anno/Programmazione_2/data_structures/bst.cc
@@ -0,0 +1,225 @@
+#include<iostream>
+
+using namespace std;
+
+template<class T>
+struct node {
+    T key;
+    node<T>* prev;
+    node<T>* right;
+    node<T>* left;
+};
+
+template<class T>
+class bst {
+public:
+    bst() : root{nullptr} {}
+
+    ~bst() {
+        // TODO
+    }
+
+    bst<T>* insert(initializer_list<T>&& list) {
+        for(auto const& i : list)
+            insert(i);
+
+        return this;
+    }
+
+    bst<T>* insert(T k) {
+        node<T>* nodus = new node<T>{k, nullptr, nullptr, nullptr};
+        node<T>* iter = root;
+        node<T>* prev = nullptr;
+
+        while(iter) {
+            prev = iter;
+            iter = (k < iter->key) ? iter->left : iter->right;
+        }
+
+        nodus->prev = prev;
+        if(!prev)
+            root = nodus;
+        else if(k < prev->key)
+            prev->left = nodus;
+        else
+            prev->right = nodus;
+
+        return this;
+    }
+
+    bst<T>* remove(initializer_list<T>&& list) {
+        for(auto const& i : list)
+            remove(i);
+
+        return this;
+    }
+
+    bst<T>* remove(T k) {
+        node<T>* nodus = search(k);
+        if(!nodus) return this;
+
+        if(!nodus->left) {
+            _transplant(nodus, nodus->right);
+        } else if(!nodus->right) {
+            _transplant(nodus, nodus->left);
+        } else {
+            node<T>* iter = _min(nodus->right);
+            if(iter->prev != nodus) {
+                _transplant(iter, iter->right);
+                iter->right = nodus->right;
+                iter->right->prev = iter;
+            }
+            _transplant(nodus, iter);
+            iter->left = nodus->left;
+            iter->left->prev = iter;
+        }
+
+        delete nodus;
+        return this;
+    }
+
+    node<T>* min() {
+        return _min(root);
+    }
+
+    node<T>* min(node<T>* nodus) {
+        return _min(nodus);
+    }
+
+    node<T>* max() {
+        return _max(root);
+    }
+
+    node<T>* max(node<T>* nodus) {
+        return _max(nodus);
+    }
+
+    node<T>* search(T k) {
+        node<T>* iter = root;
+        while(iter && iter->key != k)
+            iter = (iter->key > k) ? iter->left : iter->right;
+
+        return iter;
+    }
+
+    node<T>* successor(T k) {
+        node<T>* nodus = search(k);
+        if(!nodus) return nullptr;
+
+        if(nodus->right)
+            return min(nodus->right);
+
+        node<T>* prev = nodus->prev;
+        while(prev && nodus == prev->right) {
+            nodus = prev;
+            prev = prev->prev;
+        }
+
+        return prev;
+
+    }
+    node<T>* predecessor(T k) {
+        node<T>* nodus = search(k);
+        if(!nodus) return nullptr;
+
+        if(nodus->left)
+            return max(nodus->left);
+
+        node<T>* prev = nodus->prev;
+        while(prev && nodus == prev->left) {
+            nodus = prev;
+            prev = prev->prev;
+        }
+
+        return prev;
+    }
+
+    friend ostream& operator<<(ostream& os, bst<T>* tree) {
+        tree->_preorder(os, tree->root);
+        return os;
+    }
+private:
+    void _transplant(node<T>* u, node<T>* v) {
+        if(!u->prev) {
+            root = v;
+        } else if(u == u->prev->left) {
+            u->prev->left = v;
+        } else {
+            u->prev->right = v;
+        }
+
+        if(v)
+            v->prev = u->prev;
+    }
+
+    node<T>* _min(node<T>* root) {
+        node<T>* iter = root;
+        while(iter && iter->left)
+            iter = iter->left;
+
+        return iter;
+    }
+
+    node<T>* _max(node<T>* root) {
+        node<T>* iter = root;
+        while(iter && iter->right)
+            iter = iter->right;
+
+        return iter;
+    }
+
+    void _inorder(ostream& os, node<T>* root) {
+        if(root) {
+            _inorder(os, root->left);
+            os << root->key << ' ';
+            _inorder(os, root->right);
+        }
+    }
+
+    void _preorder(ostream& os, node<T>* root) {
+        if(root) {
+            os << root->key << ' ';
+            _inorder(os, root->left);
+            _inorder(os, root->right);
+        }
+    }
+
+    void _postorder(ostream& os, node<T>* root) {
+        if(root) {
+            _inorder(os, root->left);
+            _inorder(os, root->right);
+            os << root->key << ' ';
+        }
+    }
+    node<T>* root;
+};
+
+int main() {
+    bst<int>* b = new bst<int>{};
+
+    // b->insert(12)->insert(5)->insert(18)->insert(2)->insert(9);
+    // b->insert(15)->insert(13)->insert(17)->insert(19);
+
+    b->insert({12, 5, 18, 2, 9, 15, 13, 17, 19});
+    cout << b << endl;
+    cout << (b->search(5) != nullptr) << endl;
+    cout << (b->search(1) != nullptr) << endl;
+    cout << b->max()->key << ' ' << b->min()->key << endl;
+    for(auto const& i : {12, 9, 14, 18}) {
+        auto elem = b->successor(i);
+        if(elem)
+            cout << "(" << i << ", " << elem->key << ") ";
+    }
+    cout << endl;
+
+    for(auto const& i : {9, 2, 5, 15, 18, 12, 19}) {
+        auto elem = b->predecessor(i);
+        if(elem)
+            cout << "(" << i << ", " << elem->key << ") ";
+    }
+    cout << endl;
+    b->remove({5, 12});
+    cout << b << endl;
+
+    return 0;
+}