706. Design HashMap #
题目 #
Design a HashMap without using any built-in hash table libraries.
To be specific, your design should include these functions:
put(key, value): Insert a (key, value) pair into the HashMap. If the value already exists in the HashMap, update the value.get(key): Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.remove(key): Remove the mapping for the value key if this map contains the mapping for the key.
Example:
MyHashMap hashMap = new MyHashMap();
hashMap.put(1, 1);
hashMap.put(2, 2);
hashMap.get(1); // returns 1
hashMap.get(3); // returns -1 (not found)
hashMap.put(2, 1); // update the existing value
hashMap.get(2); // returns 1
hashMap.remove(2); // remove the mapping for 2
hashMap.get(2); // returns -1 (not found)
Note:
- All keys and values will be in the range of
[0, 1000000]. - The number of operations will be in the range of
[1, 10000]. - Please do not use the built-in HashMap library.
题目大意 #
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：
- 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。
- 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。
- remove(key)：如果映射中存在这个键，删除这个数值对。
注意：
- 所有的值都在 [1, 1000000] 的范围内。
- 操作的总数目在 [1, 10000] 范围内。
- 不要使用内建的哈希库。
解题思路 #
- 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。
代码 #
package leetcode
const Len int = 100000
type MyHashMap struct {
content [Len]*HashNode
}
type HashNode struct {
key int
val int
next *HashNode
}
func (N *HashNode) Put(key int, value int) {
if N.key == key {
N.val = value
return
}
if N.next == nil {
N.next = &HashNode{key, value, nil}
return
}
N.next.Put(key, value)
}
func (N *HashNode) Get(key int) int {
if N.key == key {
return N.val
}
if N.next == nil {
return -1
}
return N.next.Get(key)
}
func (N *HashNode) Remove(key int) *HashNode {
if N.key == key {
p := N.next
N.next = nil
return p
}
if N.next != nil {
N.next = N.next.Remove(key)
}
return N
}
/** Initialize your data structure here. */
func Constructor706() MyHashMap {
return MyHashMap{}
}
/** value will always be non-negative. */
func (this *MyHashMap) Put(key int, value int) {
node := this.content[this.Hash(key)]
if node == nil {
this.content[this.Hash(key)] = &HashNode{key: key, val: value, next: nil}
return
}
node.Put(key, value)
}
/** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
func (this *MyHashMap) Get(key int) int {
HashNode := this.content[this.Hash(key)]
if HashNode == nil {
return -1
}
return HashNode.Get(key)
}
/** Removes the mapping of the specified value key if this map contains a mapping for the key */
func (this *MyHashMap) Remove(key int) {
HashNode := this.content[this.Hash(key)]
if HashNode == nil {
return
}
this.content[this.Hash(key)] = HashNode.Remove(key)
}
func (this *MyHashMap) Hash(value int) int {
return value % Len
}
/**
* Your MyHashMap object will be instantiated and called as such:
* obj := Constructor();
* obj.Put(key,value);
* param_2 := obj.Get(key);
* obj.Remove(key);
*/