#include<stdio.h>
#include<conio.h>
 
int main() {
  	double arr[30];
  	int i;
  	double mul = 1;
  	double *ptr;
  
  	printf("\nNhap 30 phan tu: \n");
  
  	for (i = 0; i < 30; i++) {
  	    printf("Nhap a[%d] = ", i + 1);
  	    scanf("%lf", &arr[i]);
   	}
//======================================
  	// gan dia chi o nho dau tien cua mang arr cho ptr = &arr[0]
  	ptr = arr;
 	// mang trong c duoc luu tru lien tuc trong bo nho
  	// do vay ta se tro con tro ptr vao o nho tiep theo va nhan vao bien mul
   	for (i = 0; i < 30; i++) 
	{
  	    mul = mul * *ptr;
  	    ptr++;
   	}
  	printf("\nTich cac phan tu cua mang la: %lf", mul);
//======================================
	double *max=arr;
	//luu gia tri dau tien cua mang vi con tro max lam thay doi
	double b=arr[0];       
	for(i=1;i<30;i++)
	{           
   	if(*max<*(max+i)) 
			*max=*(max+i);                              
  	}   
	printf("\nPhan tu lon nhat cua mang la: %lf", *max);
//======================================
	double x,sum=0;
	//tra lai gia tri dau tien cua mang
	arr[0]=b; 
	ptr=arr;
	printf("\nNhap x = "); scanf("%lf", &x);
	for(i=0;i<30;i++)
	{
		if(*ptr>x)
		{
			sum=sum+ *ptr;
		}
		ptr++;
	}
	printf("\nTong cac phan tu cua mang lon hon x la: %lf", sum);
	return(0);
}