hello-algo/codes/cpp/chapter_hashing/array_hash_map.cpp
Yudong Jin 9563965a20
Add the codes of hashmap (#553)
of chaining and open addressing
2023-06-14 02:01:06 +08:00

153 lines
3.4 KiB
C++

/**
* File: array_hash_map.cpp
* Created Time: 2022-12-14
* Author: msk397 (machangxinq@gmail.com)
*/
#include "../utils/common.hpp"
/* 键值对 */
struct Pair {
public:
int key;
string val;
Pair(int key, string val) {
this->key = key;
this->val = val;
}
};
/* 基于数组简易实现的哈希表 */
class ArrayHashMap {
private:
vector<Pair *> buckets;
public:
ArrayHashMap() {
// 初始化数组,包含 100 个桶
buckets = vector<Pair *>(100);
}
~ArrayHashMap() {
// 释放内存
for (const auto &bucket : buckets) {
delete bucket;
}
buckets.clear();
}
/* 哈希函数 */
int hashFunc(int key) {
int index = key % 100;
return index;
}
/* 查询操作 */
string get(int key) {
int index = hashFunc(key);
Pair *pair = buckets[index];
if (pair == nullptr)
return nullptr;
return pair->val;
}
/* 添加操作 */
void put(int key, string val) {
Pair *pair = new Pair(key, val);
int index = hashFunc(key);
buckets[index] = pair;
}
/* 删除操作 */
void remove(int key) {
int index = hashFunc(key);
// 释放内存并置为 nullptr
delete buckets[index];
buckets[index] = nullptr;
}
/* 获取所有键值对 */
vector<Pair *> pairSet() {
vector<Pair *> pairSet;
for (Pair *pair : buckets) {
if (pair != nullptr) {
pairSet.push_back(pair);
}
}
return pairSet;
}
/* 获取所有键 */
vector<int> keySet() {
vector<int> keySet;
for (Pair *pair : buckets) {
if (pair != nullptr) {
keySet.push_back(pair->key);
}
}
return keySet;
}
/* 获取所有值 */
vector<string> valueSet() {
vector<string> valueSet;
for (Pair *pair : buckets) {
if (pair != nullptr) {
valueSet.push_back(pair->val);
}
}
return valueSet;
}
/* 打印哈希表 */
void print() {
for (Pair *kv : pairSet()) {
cout << kv->key << " -> " << kv->val << endl;
}
}
};
/* Driver Code */
int main() {
/* 初始化哈希表 */
ArrayHashMap map = ArrayHashMap();
/* 添加操作 */
// 在哈希表中添加键值对 (key, value)
map.put(12836, "小哈");
map.put(15937, "小啰");
map.put(16750, "小算");
map.put(13276, "小法");
map.put(10583, "小鸭");
cout << "\n添加完成后,哈希表为\nKey -> Value" << endl;
map.print();
/* 查询操作 */
// 向哈希表输入键 key ,得到值 value
string name = map.get(15937);
cout << "\n输入学号 15937 ,查询到姓名 " << name << endl;
/* 删除操作 */
// 在哈希表中删除键值对 (key, value)
map.remove(10583);
cout << "\n删除 10583 后,哈希表为\nKey -> Value" << endl;
map.print();
/* 遍历哈希表 */
cout << "\n遍历键值对 Key->Value" << endl;
for (auto kv : map.pairSet()) {
cout << kv->key << " -> " << kv->val << endl;
}
cout << "\n单独遍历键 Key" << endl;
for (auto key : map.keySet()) {
cout << key << endl;
}
cout << "\n单独遍历值 Value" << endl;
for (auto val : map.valueSet()) {
cout << val << endl;
}
return 0;
}