which is more efficient F1 or F2 ?, both give the same result, the code is C++ [Solved]

Question

int F1 (unsigned int n)
{
if (n == 0) return n;
int i, j;
for (i = j = 1; i < 2 * n - 1; i += 2, j += i);
return j;
}

int F2 (unsigned int n)
{
if (n == 0) return n;
int i, j, k;
for (i = j = 1; i < n; i++, j++)
for (k = 0; k < n; k++, j++);
return j;
}

Answer 1

Not so sure, because the addition operation j+=i uses more processing power than j++, and there are very optimized looping structures, specially in small processors (8 bit microcontrollers). So the answer will probably depend on your target circuit. In a powerful PC probably F1, in a small processor you need to count assembly instructions cycle time ;)

Answer 2

F1, it only has to run through one for loop, not multiple ones