Data-structure/BST.cpp at main · Yousef-nabil/Data-structure · GitHub

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#include "BST.h"

treenode::treenode(int x) {
    value = x;
    left = right = nullptr;
}

bst::bst() {
    root = nullptr;
    size = 0;
}

void bst::inorderRec(treenode* n) {
    if (!n) return;
    inorderRec(n->left);
    cout << n->value << " ";
    inorderRec(n->right);
}

void bst::postorderRec(treenode* n) {
    if (!n) return;
    inorderRec(n->left);
    inorderRec(n->right);
    cout << n->value << " ";
}

void bst::preorderRec(treenode* n) {
    if (!n) return;
    cout << n->value << " ";
    inorderRec(n->left);
    inorderRec(n->right);
}

void bst::insert(int x) {
    if (!size) {
        root = new treenode(x);
        size++;
    } else {
        treenode* temp = root;
        treenode* prev = nullptr;
        while (temp) {
            if (temp->value > x) {
                prev = temp;
                temp = temp->left;
            } else if (temp->value < x) {
                prev = temp;
                temp = temp->right;
            } else {
                return;
            }
        }

        if (x > prev->value) {
            prev->right = new treenode(x);
        } else {
            prev->left = new treenode(x);
        }
        size++;
    }
}

void bst::inorder() {
    inorderRec(root);
}

void bst::postorder() {
    postorderRec(root);
}

void bst::preorder() {
    preorderRec(root);
}

treenode* bst::search(int x) {
    treenode* temp = root;
    while (temp) {
        if (temp->value > x) {
            temp = temp->left;
        } else if (temp->value < x) {
            temp = temp->right;
        } else {
            return temp;
        }
    }
    return temp;
}

bool bst::deleteNode(int x) {
    treenode* temp = root;
    treenode* parent = nullptr;
    while (temp) {
        if (temp->value > x) {
            parent = temp;
            temp = temp->left;
        } else if (temp->value < x) {
            parent = temp;
            temp = temp->right;
        } else {
            break;
        }
    }
    if (!temp) return false;

    if (!temp->left || !temp->right) {
        if (temp->left) {
            if (!parent) {
                root = temp->left;
            } else if (parent->left == temp) {
                parent->left = temp->left;
            } else {
                parent->right = temp->left;
            }
        } else if (temp->right) {
            if (!parent) {
                root = temp->right;
            } else if (parent->left == temp) {
                parent->left = temp->right;
            } else {
                parent->right = temp->right;
            }
        } else {
            if (!parent) {
                root = nullptr;
            } else if (parent->left == temp) {
                parent->left = nullptr;
            } else {
                parent->right = nullptr;
            }
        }
        delete temp;
    } else {
        // handle deletion when node has two children
    }

    return true;
}