2.7

#include <iostream>
using namespace std;
void Nhap(int **,int,int);
double TrungBinhCotK(int**,int,int,int);

void Xuat(int **a,int m, int n,bool Odd = false)
{
    for (int i = 0; i < m; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            if(Odd)
            {
                if(a[i][j]  % 2 != 0) cout<<a[i][j]<<"\t";
                else cout<<"x"<<"\t";
            }
            else cout<<a[i][j]<<"\t";
        }
        cout << endl;
    }
}

int main()
{
    int n, m;
    cout << "m = "; cin >> m;
    cout << "n = "; cin >> n;
    int** a = new int* [m];
    for (int i = 0; i < m; ++i)
    {
        a[i] = new int[n];
    }
    Nhap(a,m,n);
    cout<<"Cau 3: \n";Xuat(a,m,n);
    cout<<"Cau 4: \n";Xuat(a,m,n,true);
    int k;
    do
    {
        cout<<"(0 < k <= "<<n<<") k = ";
        cin>>k;
    }while(k <= 0 || k > n);
    cout<<TrungBinhCotK(a,m,n,--k);

}
void Nhap(int **a,int m,int n)
{
    for (int i = 0; i < m; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            cout<<"a["<<i<<"]["<<j<<"] = ";
            cin>>a[i][j];
        }
    }
}

double TrungBinhCotK(int **a,int m,int n,int k)
{

    double result = 0;
    for(int i = 0; i < m;++i)
    {
        result += a[i][k];
    }
    return result/m;
}