hello-algo/codes/python/chapter_hashing/array_hash_map.py

"""
File: array_hash_map.py
Created Time: 2022-12-14
Author: msk397 (machangxinq@gmail.com)
"""

# 键值对 int->String
class Entry:
    def __init__(self, key, val):
        self.key = key
        self.val = val


# 基于数组简易实现的哈希表
class ArrayHashMap:
    def __init__(self):
        # 初始化一个长度为 100 的桶（数组）
        self.bucket = [None] * 100

    # 哈希函数
    def hashFunc(self, key):
        index = key % 100
        return index

    # 查询操作
    def get(self, key):
        index = self.hashFunc(key)
        pair = self.bucket[index]
        if pair is None:
            return None
        return pair.val

    # 添加操作
    def put(self, key, val):
        pair = Entry(key, val)
        index = self.hashFunc(key)
        self.bucket[index] = pair

    # 删除操作
    def remove(self, key):
        index = self.hashFunc(key)
        # 置为空字符，代表删除
        self.bucket[index] = None

    # 获取所有键值对
    def entrySet(self):
        result = []
        for pair in self.bucket:
            if pair is not None:
                result.append(pair)
        return result

    # 获取所有键
    def keySet(self):
        result = []
        for pair in self.bucket:
            if pair is not None:
                result.append(pair.key)
        return result

    # 获取所有值
    def valueSet(self):
        result = []
        for pair in self.bucket:
            if pair is not None:
                result.append(pair.val)
        return result

    # 打印哈希表
    def print(self):
        for pair in self.bucket:
            if pair is not None:
                print(pair.key, "->", pair.val)


if __name__ == "__main__":
    """ 初始化哈希表 """
    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")
    print("\n添加完成后，哈希表为\nKey -> Value")
    Map.print()

    """ 查询操作 """
    # 向哈希表输入键 key ，得到值 value
    name = Map.get(15937)
    print("\n输入学号 15937 ，查询到姓名 " + name)

    """ 删除操作 """
    # 在哈希表中删除键值对 (key, value)
    Map.remove(10583)
    print("\n删除 10583 后，哈希表为\nKey -> Value")
    Map.print()

    """ 遍历哈希表 """
    print("\n遍历键值对 Key->Value")
    for pair in Map.entrySet():
        print(pair.key, "->", pair.val)

    print("\n单独遍历键 Key")
    for key in Map.keySet():
        print(key)

    print("\n单独遍历值 Value")
    for val in Map.valueSet():
        print(val)