main.cpp

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#include <bits/stdc++.h>
 
#define SIZE 100 // consider larger value, confront with overall performance for given use case
 
using namespace std;
 
class MyHashMap
{
private:
    // Hashtable. Array of lists of pairs (key, value)
    vector<list<pair<int, int>>> table;
 
    int hash(int key) { return key % SIZE; }
 
public:
    // Initialized my hashmap
    MyHashMap() : table(SIZE) {}
 
    void put(int key, int value)
    {
        int h = hash(key);
        for (auto& p : table[h])
            if (p.first == key)
            {
                p.second = value;
                return;
            }
        table[h].emplace_back(key, value);
    }
 
    int get(int key)
    {
        int h = hash(key);
        for (const auto& p : table[h])
            if (p.first == key)
                return p.second;
        return -1;
    }
 
    void remove(int key)
    {
        int h = hash(key);
        table[h].remove_if([key](const pair<int, int>& p) { return p.first == key; });
    }
};
 
int main()
{
    MyHashMap* obj = new MyHashMap();
    obj->put(1, 1);
    obj->put(2, 2);
    int value = obj->get(1);
    cout << value << endl;
    value = obj->get(3);
    cout << value << endl;
    obj->put(2, 1);
    value = obj->get(2);
    cout << value << endl;
    obj->remove(2);
    value = obj->get(2);
    cout << value << endl;
    delete obj;
}