数组做法：

定义数组：
		int**a = new int*[3];
		for (int i = 0;i < 3;i++)
		{
			a[i] = new int[4];
		}
		for (int i = 0;i < 3;i++)
		{
			for (int j = 0;j < 4;j++)
			{
				cin >> a[i][j];
			}
		}
释放内存：
		for (int i = 0;i < 3;i++)
		{
			delete[]a[i];
		}
		delete[]a;

vector容器做法：

  int n = 3, m = 4;
vector<vector<int> > a(n, vector<int>(m)); //定义二维动态数组3行4列 
for (int i = 0; i < a.size(); i++)//输入二维动态数组 
{
    for (int j = 0;j < a[i].size();j++)
    {
        cin >> a[i][j];
    }
}