RosettaCodeData/Task/Find-the-missing-permutation/Zkl/find-the-missing-permutation.zkl

var data=L("ABCD","CABD","ACDB","DACB","BCDA","ACBD","ADCB","CDAB",
           "DABC","BCAD","CADB","CDBA","CBAD","ABDC","ADBC","BDCA",
           "DCBA","BACD","BADC","BDAC","CBDA","DBCA","DCAB");
Utils.Helpers.permute(["A".."D"]).apply("concat").copy().remove(data.xplode());