#include<stdio.h>
#include<conio.h>
#include<math.h>
#define MAX 100

void nhap (int a[], int &n)
{
	do
	{
		printf("\nNhap so phan tu: ");
		scanf("%d", &n);
		if(n <= 0 || n > MAX)
		{
			printf("\nSo phan tu khong hop le. Xin kiem tra lai !");
		}
	}while(n <= 0 || n > MAX);
	for(int i = 0; i < n; i++)
	{
		printf("\nNhap a[%d]: ", i);
		scanf("%d", &a[i]);
	}
}

void xuat(int a[], int n)
{
	for(int i = 0; i < n; i++)
	{
		printf("%4d", a[i]);
	}
}


void LietKeTanSuatXuatHien(int a[], int n)
{
	for(int i = 0; i < n; i++)
	{
		int dem = 0;
		for(int j = 0; j < n; j++) // j chạy từ 0
		{
			if(a[i] == a[j])
			{
				if(i <= j)         
				{
					dem++;    
				}
				else
				{
					break;    // bỏ qua phần tử bị trùng
				}
			}
		}
		if(dem != 0)
		{
			printf("\nGia tri %d co tan suat xuat hien la %d", a[i], dem);
		}
	}
}
int main()
{
	int n;
	int a[MAX];

	nhap(a, n);
	xuat(a, n);
	LietKeTanSuatXuatHien(a, n);

	getch();
	return 0;
}

Line 17: error: conio.h: No such file or directory
Line 6: error: expected ';', ',' or ')' before '&' token
In function 'xuat':
Line 26: error: 'for' loop initial declaration used outside C99 mode
In function 'LietKeTanSuatXuatHien':
Line 35: error: 'for' loop initial declaration used outside C99 mode
Line 38: error: 'for' loop initial declaration used outside C99 mode