C#LeetCode刷题之#706-设计哈希映射（Design HashMap）

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。

MyHashMap hashMap = new MyHashMap();

hashMap.put(1, 1);

hashMap.put(2, 2);

hashMap.get(1);            // 返回 1

hashMap.get(3);            // 返回 -1 (未找到)

hashMap.put(2, 1);         // 更新已有的值

hashMap.get(2);            // 返回 1

hashMap.remove(2);         // 删除键为2的数据

hashMap.get(2);            // 返回 -1 (未找到)

Design a HashMap without using any built-in hash table libraries.

To be specific, your design should include these two 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.

MyHashMap hashMap = new MyHashMap();

hashMap.put(1, 1);

hashMap.put(2, 2);

hashMap.get(1);            // returns 1

hashMap.put(2, 1);          // update the existing value

hashMap.get(2);            // returns 1

hashMap.remove(2);          // remove the mapping for 2

Note:

All values will be in the range of [1, 1000000].
The number of operations will be in the range of [1, 10000].
Please do not use the built-in HashMap library.

```public class Program {

public static void Main(string[] args) {
var hashMap = new MyHashMap();

hashMap.Put(1, 1);
hashMap.Put(2, 2);
hashMap.Get(1);
hashMap.Get(3);
hashMap.Put(2, 1);
hashMap.Get(2);
hashMap.Remove(2);
hashMap.Get(2);

}

public class MyHashMap {

private int[] buckets;

public MyHashMap() {
buckets = new int[1000000];
for(var i = 0; i < buckets.Length; i++) {
buckets[i] = -1;
}
}

private int GetHashCode(int key) {
//用本身值作为散列值
return key;
}

public void Put(int key, int value) {
buckets[GetHashCode(key)] = value;
}

public int Get(int key) {
var res = buckets[GetHashCode(key)];
Console.WriteLine(res);
return res;
}

public void Remove(int key) {
buckets[GetHashCode(key)] = -1;
}

}

}```

```1
-1
1
-1```

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