Rohit Gupta :
In c++ permutations of an array can be generated using the function next_permutation. Is there a java equivalent of such a function to generate permutations of a size N array?
I am trying to come up with an equivalent recursive implementation but am struggling to solidify my logic.
loganrussell48 :
There isn't a built-in function like this in java. You'll have to create your own, which is not that complicated. I'll provide an edit to this answer momentarily with a solution (not necessarily the best solution)
public static void printperms(int[] perm, boolean[] used, int k)
{
if (k == perm.length) print(perm);
for (int i=0; i<perm.length; i++) {
if (!used[i]) {
used[i] = true;
perm[k] = i;
printperms(perm, used, k+1);
used[i] = false;
}
}
}
you can then create a new method, like so, to call it:
public void perms(int n){
printperms(new int[n], new boolean[n], 0);
}
Lastly, where I have the print method, you can have the Array added to a list instead so that you can collect them all in a list, or you can just print it out. Your choice. Do with it as you please.
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