Mảng C++( BASSIC )

#include <iostream>
#define MAX 100
using namespace std;
void nhapmang(int a[], int &n)
{
	do
	{
		cout << "nhap so luong mang = ";
		cin >> n;
		if (n<0 || n>MAX)
		{
			cout << "so luong mang nhap sai,xin moi nhap lai"<<endl;
		}
	} while (n<0 || n>MAX);
	for (int i = 0; i < n; i++)
	{
		cout << "Nhap A[" << i << "]:";
		cin >> a[i];
	}
}
void xuatmang(int a[], int &n)
{
	for (int i= 0; i < n; i++)
	{
		cout << "    " << a[i];
	}
	cout << "\n";
}
int ktphantunhonhat(int a[], int &n)// tim phan tu nho nhat trong mang
{
	int min = a[0];
	for (int i = 0; i < n; i++)
	{
		if (a[i] < min)
		{
			min = a[i];
		}
	}
	return min;
}
int ktphantulonnhat(int a[], int &n)// tim phan tu lon nhat trong mang
{
	int max = a[0];
	for (int i = 0; i < n; i++)
	{
		if (a[i] > max)
		{
			max = a[i];
		}
	}
	return max;
}
int sxmanggiamdan(int a[], int &n)
{
	int giamdan;
	for (int i = 0; i < n - 1; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (a[i] < a[j])
			{
				giamdan = a[i];
				a[i] = a[j];
				a[j] = giamdan;
			}
		}
	}
	return giamdan;
}
int sxmangtangdan(int a[], int &n)
{
	int tangdan;
	for (int i = 0; i < n - 1; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (a[i] > a[j])
			{
				tangdan = a[i];
				a[i] = a[j];
				a[j] = tangdan;
			}
		}
	}
	return tangdan;
}
void main()
{
	int a[MAX];
	int n;
	nhapmang(a, n);
	xuatmang(a, n);
	cout << "phan tu nho nhat trong mang la:" << ktphantunhonhat(a, n) << endl;
	cout << "phan tu lon nhat trong mang la: " << ktphantulonnhat(a, n) << endl;
	sxmanggiamdan(a, n);
	cout << "mang da sap xep theo thu tu giam dan la: ";
	xuatmang(a, n);
	sxmangtangdan(a, n);
	cout << "mang da sap xep theo thu tu tang dan la: ";
	xuatmang(a, n);
	system("\npause");
}