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151 lines
3.8 KiB
Markdown
Executable File
151 lines
3.8 KiB
Markdown
Executable File
# [706. Design HashMap](https://leetcode.com/problems/design-hashmap/)
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## 题目
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Design a HashMap without using any built-in hash table libraries.
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To be specific, your design should include these functions:
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- `put(key, value)` : Insert a (key, value) pair into the HashMap. If the value already exists in the HashMap, update the value.
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- `get(key)`: Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.
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- `remove(key)` : Remove the mapping for the value key if this map contains the mapping for the key.
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**Example**:
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MyHashMap hashMap = new MyHashMap();
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hashMap.put(1, 1);
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hashMap.put(2, 2);
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hashMap.get(1); // returns 1
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hashMap.get(3); // returns -1 (not found)
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hashMap.put(2, 1); // update the existing value
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hashMap.get(2); // returns 1
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hashMap.remove(2); // remove the mapping for 2
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hashMap.get(2); // returns -1 (not found)
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**Note**:
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- All keys and values will be in the range of `[0, 1000000]`.
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- The number of operations will be in the range of `[1, 10000]`.
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- Please do not use the built-in HashMap library.
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## 题目大意
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不使用任何内建的哈希表库设计一个哈希映射具体地说，你的设计应该包含以下的功能：
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- put(key, value)：向哈希映射中插入(键,值)的数值对。如果键对应的值已经存在，更新这个值。
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- get(key)：返回给定的键所对应的值，如果映射中不包含这个键，返回 -1。
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- remove(key)：如果映射中存在这个键，删除这个数值对。
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注意：
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- 所有的值都在 [1, 1000000] 的范围内。
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- 操作的总数目在 [1, 10000] 范围内。
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- 不要使用内建的哈希库。
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## 解题思路
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- 简单题，设计一个 hashmap 的数据结构，要求有 `put(key, value)`，`get(key)`，`remove(key)`，这 3 个方法。设计一个 map 主要需要处理哈希冲突，一般都是链表法解决冲突。
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## 代码
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```go
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package leetcode
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const Len int = 100000
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type MyHashMap struct {
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content [Len]*HashNode
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}
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type HashNode struct {
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key int
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val int
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next *HashNode
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}
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func (N *HashNode) Put(key int, value int) {
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if N.key == key {
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N.val = value
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return
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}
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if N.next == nil {
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N.next = &HashNode{key, value, nil}
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return
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}
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N.next.Put(key, value)
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}
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func (N *HashNode) Get(key int) int {
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if N.key == key {
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return N.val
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}
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if N.next == nil {
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return -1
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}
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return N.next.Get(key)
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}
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func (N *HashNode) Remove(key int) *HashNode {
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if N.key == key {
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p := N.next
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N.next = nil
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return p
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}
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if N.next != nil {
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return N.next.Remove(key)
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}
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return nil
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}
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/** Initialize your data structure here. */
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func Constructor706() MyHashMap {
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return MyHashMap{}
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}
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/** value will always be non-negative. */
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func (this *MyHashMap) Put(key int, value int) {
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node := this.content[this.Hash(key)]
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if node == nil {
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this.content[this.Hash(key)] = &HashNode{key: key, val: value, next: nil}
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return
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}
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node.Put(key, value)
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}
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/** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
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func (this *MyHashMap) Get(key int) int {
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HashNode := this.content[this.Hash(key)]
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if HashNode == nil {
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return -1
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}
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return HashNode.Get(key)
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}
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/** Removes the mapping of the specified value key if this map contains a mapping for the key */
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func (this *MyHashMap) Remove(key int) {
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HashNode := this.content[this.Hash(key)]
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if HashNode == nil {
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return
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}
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this.content[this.Hash(key)] = HashNode.Remove(key)
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}
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func (this *MyHashMap) Hash(value int) int {
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return value % Len
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}
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/**
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* Your MyHashMap object will be instantiated and called as such:
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* obj := Constructor();
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* obj.Put(key,value);
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* param_2 := obj.Get(key);
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* obj.Remove(key);
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*/
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``` |