int efcz(int a[], int n, int x)
{
int low = 0;
int high = n-1;
int mid;
do
{
mid = (low + high) / 2;
if(x == a[mid])
return 1;
else if(x > a[mid])
low = mid + 1;
else
high = mid - 1;
}while(low <= high);
return 0;
}
void main()
{
int a[] ={3,5,10,12,17,20,23,27,31,34,39,40,41};
int x;
printf("please input x: ");
scanf("%d",&x);
if(efcz(a,13,x))
printf("%d is found\n",x);
else
printf("%d not element\n",x);
}