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| #include <functional>
#include <iostream>
#include <optional>
#include <string>
#include <vector>
template <typename T>
concept Comparable = requires(T a, T b) {
{ a < b } -> std::convertible_to<bool>;
{ a > b } -> std::convertible_to<bool>;
{ a == b } -> std::convertible_to<bool>;
};
template <typename T>
concept Streamable = requires(T a, std::ostream& os) {
{ os << a } -> std::same_as<std::ostream&>;
};
template <Comparable K, Streamable V>
class PairBSTree {
private:
using Pair = std::pair<K, V>;
struct TreeNode {
Pair _pair;
TreeNode* _left;
TreeNode* _right;
TreeNode() = default;
TreeNode(const Pair& pair)
: _pair(pair), _left(nullptr), _right(nullptr) {}
TreeNode(Pair&& pair)
: _pair(std::move(pair)), _left(nullptr), _right(nullptr) {}
~TreeNode() = default;
};
TreeNode* _root;
void build_(const std::vector<Pair>& nodes) {
for (const auto& pair : nodes) {
Insert(pair);
}
}
void build_(std::vector<Pair>&& nodes) {
for (Pair& pair : nodes) {
Insert(std::move(pair));
}
}
void destroy_(TreeNode* node) {
if (node) {
destroy_(node->_left);
destroy_(node->_right);
delete node;
node = nullptr;
}
}
TreeNode*& search_(TreeNode*& node, K key) const {
if (!node || key == node->_pair.first) {
return node;
}
if (key < node->_pair.first) {
return search_(node->_left, key);
}
return search_(node->_right, key);
}
void insert_(TreeNode*& node, const Pair& pair) {
if (!node) {
node = new TreeNode(pair);
return;
}
auto key = pair.first;
if (key == node->_pair.first) {
node->_pair = pair;
} else if (key < node->_pair.first) {
insert_(node->_left, pair);
} else {
insert_(node->_right, pair);
}
}
TreeNode*& go_to_max_(TreeNode*& node) {
while (node->_right) {
node = node->_right;
}
return node;
}
TreeNode*& go_to_min_(TreeNode*& node) {
while (node->_left) {
node = node->_left;
}
return node;
}
void delete_(TreeNode*& node, K key) {
auto& target = search_(node, key);
if (!target) {
return;
}
if (!target->_left && !target->_right) {
delete target;
target = nullptr;
return;
}
if (!target->_left) {
TreeNode* temp = target->_right;
delete target;
target = temp;
return;
}
if (!target->_right) {
TreeNode* temp = target->_left;
delete target;
target = temp;
return;
}
auto& max_in_left = go_to_max_(target->_left);
target->_pair = max_in_left->_pair;
// 1. 常规的递归，把整个左子树当做新的树
// delete_(target->_left, max_in_left->_pair.first);
// 2. 直接传入 max_in_left 即可
// delete_(max_in_left, max_in_left->_pair.first);
// 3. 实际上不需要递归，因为 max_in_left 是左边最大的值，一定没有右子树
TreeNode* temp = max_in_left->_left;
delete max_in_left;
max_in_left = temp;
// 我开始时候的代码（有误）：
// auto& max_in_left = go_to_max_(node->_left); // 应该是
// current->_left current->_pair = max_in_left->_pair; delete
// (max_in_left); max_in_left = nullptr;
// 第三种和我开始时候的逻辑类似
// 但我当时忘了保留 max_in_left 的左子树（如果存在）
}
static void normal_print_func_(const Pair& pair) {
std::cout << pair.second << " | ";
}
void in_order_(TreeNode* node, std::function<void(const Pair&)> func) {
if (!node) {
return;
}
in_order_(node->_left, func);
func(node->_pair);
in_order_(node->_right, func);
}
public:
PairBSTree() : _root(nullptr) {}
PairBSTree(const std::vector<Pair>& pairs) : _root(nullptr) {
build_(pairs);
}
PairBSTree(std::vector<Pair>&& pairs) : _root(nullptr) {
build_(std::move(pairs));
}
~PairBSTree() { destroy_(_root); }
std::optional<V> Search(K key) {
auto node = search_(_root, key);
if (!node) {
return std::nullopt;
}
return node->_pair.second;
}
void Insert(const Pair& pair) { insert_(_root, pair); }
void Delete(K key) { delete_(_root, key); }
void InOrder(std::function<void(Pair)> func = normal_print_func_) {
in_order_(_root, func);
}
[[nodiscard]] size_t Size() {
size_t size = 0;
InOrder([&size](std::pair<K, V>) { ++size; });
return size;
}
[[nodiscard]] V Max() {
auto temp = _root;
go_to_max_(temp);
return temp->_pair.second;
}
[[nodiscard]] V Min() {
auto temp = _root;
go_to_min_(temp);
return temp->_pair.second;
}
};
int main(void) {
std::vector<std::pair<int, std::string>> pairs = {
{2, "Bob"}, {9, "Jack"}, {4, "Lucy"}, {23, "Evan"},
{3, "Gorge"}, {12, "Lily"}, {15, "Mono"}, {90, "Rick"},
{14, "Lance"}, {76, "Molly"}, {24, "Stan"}, {11, "Scot"},
{54, "Mint"}, {37, "Biance"}, {35, "Cower"}, {1, "Brick"},
};
PairBSTree tree(pairs);
std::cout << "Name of 9: " << tree.Search(9).value_or("nothing") << '\n';
std::cout << "Size: " << tree.Size() << '\n';
// std::cout << "Min: " << tree.Min() << '\n';
// std::cout << "Max: " << tree.Max() << '\n';
tree.InOrder();
std::cout << '\n';
tree.Delete(15);
std::cout << "Size: " << tree.Size() << '\n';
tree.InOrder();
std::cout << '\n';
std::vector<std::string> names_in_order;
tree.InOrder([&names_in_order](std::pair<int, std::string> pair) {
std::cout << pair.second << " -- ";
names_in_order.push_back(pair.second);
});
std::cout << std::endl;
return 0;
}
|
