int fib_rec(int n)
{
int rez;
if (n < 2)
return 1;
rez = fib_rec(n-1) + fib_rec(n-2);
return rez;
}
void
fib(void)
{
msg_t msg_struct;
msg_t *msg = &msg_struct;
int n = 0;
int i = 0;
read_message_by_type(msg, MSG_TYPE_ARGUMENT, 100);
if (msg_type_is_invalid(msg))
{
print_usage();
return;
}
n = atoi(msg_data_get_string(msg));
if (n <= 0)
{
print_usage();
return;
}
for (i = 0; i <= n; ++i)
{
sleep(100);
print_str("fib(");
print_int(i);
print_str(") = ");
print_int(fib_rec(i));
print_strln("");
}
}
/* Calculate the nth fibonacci number and print it to the kernel log */
static int fib_calculate(struct file *file, const char *user_buffer,
unsigned long buf_count, void *data)
{
int n, i, fib1=0, fib2=1, tmp;
char kernel_buf[10]; /* Expect max 10 chars */
char *endp;
if (buf_count > sizeof(kernel_buf))
return -EINVAL;
/* Copy data from user-space via proc file entry */
if (copy_from_user(kernel_buf, user_buffer, buf_count))
{
printk ("Copy from user error\n");
return -EFAULT;
}
n = (int)(simple_strtoul(kernel_buf, &endp, 10));
if (*endp != '\n')
{
return -EINVAL;
}
if(n<=0)
printk("Invalid value entered\n");
else
{
fib1=fib_rec(n);
printk("The %dth Fibonacci number is: %d\n",n,fib1);
}
return buf_count;
}
int fib_rec(const int& n, std::vector<int>& memo, long long& count) {
assert(n >= 0);
// base cases
if (n <= 1)
return n;
// set the elements using memoization
if (memo[n - 1] == -1)
memo[n - 1] = fib_rec(n - 1, memo, ++count);
if (memo[n - 2] == -1)
memo[n - 2] = fib_rec(n - 2, memo, ++count);
// return the two elements added together after they are computed
return memo[n - 1] + memo[n - 2];
}
int main(int argc, char* argv[]) {
assert(argc == 2);
long long count = 0;
int target = atoi(argv[1]);
std::vector<int> memo(target + 1, -1);
for (int i = 0; i <= target; ++i)
std::cout << "[" << fib_rec(i, memo, ++count) << "]";
std::cout << std::endl << "Function calls: " << count << std::endl;
}
static int
fib_rec(int n)
{
return (n <= 1) ? 1 : fib_rec(n-1) + fib_rec(n-2);
}
void print_fibs(int n)
{
printf("fib(%d) rec=%d nerec=%d\n", n, fib_rec(n), fib_nerec(n));
}
