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Task/Find-the-missing-permutation/EchoLisp/find-the-missing-permutation.echolisp

@@ -0,0 +1,14 @@
+;; use the obvious methos
+(lib 'list) ; for (permutations) function
+
+;; input
+(define perms '
+(ABCD CABD ACDB DACB BCDA ACBD ADCB CDAB DABC BCAD CADB CDBA CBAD ABDC ADBC BDCA DCBA BACD BADC BDAC CBDA DBCA DCAB))
+
+;; generate all permutations
+(define all-perms (map list->string (permutations '(A B C D))))
+   → all-perms
+
+;; {set} substraction
+(set-substract (make-set all-perms) (make-set perms))
+  → { DBAC }