10395 - Titans in Danger

[inteplus]

Yes, weird description.

I guess this is what the author hid.
Suppose you use recursive function f(n) to generate permutations of the first n Titans. When you decide which guy to swap with the rightmost.
- n odd: Make the leftmost guy happy.
- n even: Blindly select one-by-one, left-to-right.

Thanks to Adrian and Snap. I got AC.

[windows2k]

Suppose you use recursive function f(n) to generate permutations of the first n Titans. When you decide which guy to swap with the rightmost.
- n odd: Make the leftmost guy happy.
- n even: Blindly select one-by-one, left-to-right.

Sorry , I don't understand what you mean
Could you explain more clearly , or take "abcd" for example
thx in advance

[gagern]

See also Topic 1866.

I also tried this simple recursion:

Code: Select all

perm(0): output current
perm(i): perm(i-1);
         for j=1 to i: swap 0 and i;
                       perm(i-1);

Result: some permutations occur several times, up to 36. Thus others must be missing.

Greetings!

[inva1id]

Arighty! Finally got accepted on my own... This thread can be deleted