Computational Complexity (Big O Notation)

I've been trying to learn more about Big O Notation and I've gotten stuck on a few pieces of code. What is the computational complexity for the following pieces of code?

1:

for(int i = n; i > 0; i /= 2) {
for(int j = 1; j < n; j *= 2) {
for(int k = 0; k < n; k += 2) {
// constant number of operations

[Code] .....

5 : Determine the average processing time of the recursive algorithm. (int n) spends one time unit to return a random integer value uniformly distributed in the range [0,n] whereas all other instructions spend a negligibly small time(e.g., T(0) = 0)

int myTest(int n) {
if(n <= 0) return 0;
else {
int i = random(n - 1);
return myTest(i) + myTest(n - 1 - i);

6 : Assume array a contains n values, the method randomValue takes a constant number c of computational steps to produce each output value, and that the method goodSort takes n log n computational steps to sort the array.

for(i = 0; i < n; i++) {
for(j = 0; j < n; j++)
a[j] = randomValue(i);
goodSort(a);
}