vector

#include<iostream>
 
using namespace std;
 
class VectorNode {
public:
    int value, key;
};
 
 
class Vector {
public:
    int cnt, reserved;
    VectorNode *nodes;
 
 
    void Resize() {
        reserved *= 2;
        VectorNode *tmp = new VectorNode[reserved];
 
        for (int i = 0; i < reserved / 2; i++)
            tmp[i] = nodes[i];
 
        delete[] nodes;
        nodes = tmp;
    }
 
    Vector() {
        cnt = 0;
        reserved = 4;
        nodes = new VectorNode[reserved];        
    }
 
    ~Vector() {
        delete[] nodes;
    }
 
    void PushBack(int key, int value) {
        if (cnt >= reserved)
            Resize();
 
        nodes[cnt].key = key;
        nodes[cnt].value = value;
        cnt++;
    }
 
    void Clear() {
        delete[] nodes;
        cnt = 0;
        reserved = 4;
        nodes = new VectorNode[reserved];
    }
};
 
int main(void) {
    Vector vector;
    for (int i = 0; i < 20; i++) {
        vector.PushBack(i, i);
    }
 
 
    for (int i = 0; i < 20; i++) {
        cout << vector.nodes[i].value << " ";
    }
 
    return 0;
}