Java Code for permutations of a list of numbers

Question

I have written a program to find all the possible permutations of a given list of items. This precisely means that my program prints all possible P(n,r) values for r=0 to n<

Answer 1

If you're not storing it -- if you're just iterating through it -- then consider using Heap's algorithm (#3 on http://www.cut-the-knot.org/do_you_know/AllPerm.shtml) -- or, just to make your life easier, use Guava's Collections2.permutations, which doesn't actually construct the whole list of permutations -- it walks through them on the fly. (Disclosure: I contribute to Guava.)