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706. 设计哈希映射

English Version

题目描述

不使用任何内建的哈希表库设计一个哈希映射（HashMap）。

实现 MyHashMap 类：

  • MyHashMap() 用空映射初始化对象
  • void put(int key, int value) 向 HashMap 插入一个键值对 (key, value) 。如果 key 已经存在于映射中，则更新其对应的值 value 。
  • int get(int key) 返回特定的 key 所映射的 value ；如果映射中不包含 key 的映射，返回 -1 。
  • void remove(key) 如果映射中存在 key 的映射，则移除 key 和它所对应的 value 。

 

示例：

输入：
["MyHashMap", "put", "put", "get", "get", "put", "get", "remove", "get"]
[[], [1, 1], [2, 2], [1], [3], [2, 1], [2], [2], [2]]
输出：
[null, null, null, 1, -1, null, 1, null, -1]

解释：
MyHashMap myHashMap = new MyHashMap();
myHashMap.put(1, 1); // myHashMap 现在为 [[1,1]]
myHashMap.put(2, 2); // myHashMap 现在为 [[1,1], [2,2]]
myHashMap.get(1);    // 返回 1 ，myHashMap 现在为 [[1,1], [2,2]]
myHashMap.get(3);    // 返回 -1（未找到），myHashMap 现在为 [[1,1], [2,2]]
myHashMap.put(2, 1); // myHashMap 现在为 [[1,1], [2,1]]（更新已有的值）
myHashMap.get(2);    // 返回 1 ，myHashMap 现在为 [[1,1], [2,1]]
myHashMap.remove(2); // 删除键为 2 的数据，myHashMap 现在为 [[1,1]]
myHashMap.get(2);    // 返回 -1（未找到），myHashMap 现在为 [[1,1]]

 

提示：

  • 0 <= key, value <= 106
  • 最多调用 104 次 put、get 和 remove 方法

解法

数组实现。

Python3

class MyHashMap:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.data = [-1] * 1000001

    def put(self, key: int, value: int) -> None:
        """
        value will always be non-negative.
        """
        self.data[key] = value

    def get(self, key: int) -> int:
        """
        Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
        """
        return self.data[key]

    def remove(self, key: int) -> None:
        """
        Removes the mapping of the specified value key if this map contains a mapping for the key
        """
        self.data[key] = -1



# Your MyHashMap object will be instantiated and called as such:
# obj = MyHashMap()
# obj.put(key,value)
# param_2 = obj.get(key)
# obj.remove(key)

Java

class MyHashMap {

    private int[] data;

    /** Initialize your data structure here. */
    public MyHashMap() {
        data = new int[1000001];
        Arrays.fill(data, -1);
    }

    /** value will always be non-negative. */
    public void put(int key, int value) {
        data[key] = value;
    }

    /** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
    public int get(int key) {
        return data[key];
    }

    /** Removes the mapping of the specified value key if this map contains a mapping for the key */
    public void remove(int key) {
        data[key] = -1;
    }
}

/**
 * Your MyHashMap object will be instantiated and called as such:
 * MyHashMap obj = new MyHashMap();
 * obj.put(key,value);
 * int param_2 = obj.get(key);
 * obj.remove(key);
 */

TypeScript

class MyHashMap {
    data: Array<number>;
    constructor() {
        this.data = new Array(10 ** 6 + 1).fill(-1);
    }

    put(key: number, value: number): void {
        this.data[key] = value;
    }

    get(key: number): number {
        return this.data[key];
    }

    remove(key: number): void {
        this.data[key] = -1;
    }
}

/**
 * Your MyHashMap object will be instantiated and called as such:
 * var obj = new MyHashMap()
 * obj.put(key,value)
 * var param_2 = obj.get(key)
 * obj.remove(key)
 */

...