NUPerms

Next Unique Permutation of an integer vector

[PermOut, last] = NUPerms(PermIn) uses a simple and efficient iterative algorithm to return the permutation vector that follows PermIn in lexicographical order, discarding replicates.

This is much faster than finding all permutations with perms and then discarding replicates. Moreover, calling the function iteratively, one can explore all permutations of a given vector without having to store them in memory.

If PermIn is the last vector in lexicographical order, then PermOut=PermIn and last is set to 1, otherwise last is set to 0.

[P,last]=NUPerms([0 0 1])
P = 0 1 0
last = 0

[P,last]=NUPerms([1 0 0])
P = 1 0 0
last = 1