Likou 706. Design Hash Mapping Hash (Chain Address Method)

https://leetcode-cn.com/problems/design-hashmap/

思路：$vector+forward\_list$ , the chain address method is sufficient.

class node
{
    
    
public:
    int key,value;
    node(int k=0,int v=0):key(k),value(v){
    
    }
};

class MyHashMap {
    
    
public:
    /** Initialize your data structure here. */
    const int num=2333;
    vector<forward_list<node>> table;

    MyHashMap() {
    
    
        table.resize(num);
    }
    
    /** value will always be non-negative. */
    void put(int key, int value) {
    
    
        int idx=key%num;
        auto it=table[idx].begin(),ed=table[idx].end();
        while(it!=ed)
        {
    
    
            if(it->key==key)
            {
    
    
                it->value=value;
                return;
            }
            ++it;
        }
        table[idx].emplace_front(key,value);
    }
    
    /** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
    int get(int key) {
    
    
        int idx=key%num;
        auto it=table[idx].begin(),ed=table[idx].end();
        while(it!=ed)
        {
    
    
            if(it->key==key)
                return it->value;
            ++it;
        }
        return -1;
    }
    
    /** Removes the mapping of the specified value key if this map contains a mapping for the key */
    void remove(int key) {
    
    
        int idx=key%num;
        auto it=table[idx].before_begin(),nxt=table[idx].begin(),ed=table[idx].end();
        while(nxt!=ed)
        {
    
    
            if(nxt->key==key)
            {
    
    
                table[idx].erase_after(it);
                return ;
            }
            it=nxt++;
        }
    }
};

/**
 * 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);
 */