Recursion with binary numbers

Question

I need to print out a list of all possiblle binary numbers with as many digits as an int k. For example, if k = 3, it would need to print out 000,001,010,011,100,101,110,111. for k = 2 it is only 00, 01, 10, 11. It is pretty clear that for any k, a recursive technique can be used to solve this problem, but I'm having trouble finding the solution. Please help. Thanks

Answer 1

You don't need recursion:for (int i = 0, max = 1 << (k - 1); i < max; ++i) {
  print binary i to k digits
}But a recursive approach would be void increment (int[] data, int digit) {
if (digit > 0) {
--digit;
for (int i = 0; i < 2; ++i) {
  data[digit] = i;
  increment(data, digit);
} else {
print contents of data array
start (int k) { increment(new int[k], k); }Neither code tested.
Pete