permutation(p1 = v1) public

When invoked with a block, yield all permutations of length n of the elements of ary, then return the array itself. If n is not specified, yield all permutations of all elements. The implementation makes no guarantees about the order in which the permutations are yielded.

When invoked without a block, return an enumerator object instead.


a = [1, 2, 3]
a.permutation.to_a     #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
a.permutation(1).to_a  #=> [[1],[2],[3]]
a.permutation(2).to_a  #=> [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]]
a.permutation(3).to_a  #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
a.permutation(0).to_a  #=> [[]] # one permutation of length 0
a.permutation(4).to_a  #=> []   # no permutations of length 4
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