2.1

#include <iostream>
using namespace std;
void Nhap(float[],int);
void Xuat(float[],int);
void Cau4(float[],int);
void Cau5(float[],int);
int main()
{
    int n;
    cout<<"n = ";
    cin>>n;
    float *a = new float[n];
    Nhap(a,n);
    cout<<"Cau 3 :"<<endl;
    Xuat(a,n);
    cout<<"Cau 4 :"<<endl;
    Cau4(a,n);
    cout<<"Cau 5 :"<<endl;
    Cau5(a,n);
    delete[] a;
    return 0;
}
void Nhap(float a[],int n)
{
    for(int i =0; i < n; ++i)
    {
        cout<<"a["<<i<<"] = ";
        cin>>a[i];
    }
}
void Xuat(float a[],int n)
{
    for(int i =0; i < n; ++i)
    {
        cout<<a[i]<<"\t";
    }
    cout<<endl;
}
void Cau4(float a[],int n)
{
    for(int i =0; i < n; ++i)
    {
        if(a[i] > 0)
        {
            cout<<a[i]<<"\t";
        }
    }
    cout<<endl;
}
void Cau5(float a[],int n)
{
    float Sum = 0;
    int count = 0;
    for(int i =0; i < n; ++i)
    {
        if(a[i] > 0)
        {
            Sum +=a[i];
            count++;
        }
    }
    cout<<"Trung binh cong cac so duong : "<<Sum/count<<endl;
}