Revision as of 17:37, 3 November 2010 (view source) Toucan (talk \| contribs) (→‎{{header\|OCaml}}) ← Older edit		Revision as of 17:45, 3 November 2010 (view source) Toucan (talk \| contribs) (two methods) Newer edit →
Line 3: (c.f. [[Permutations]]) There is an obvious method : enumerating all permutations of A, B, C, D, and looking for the missing one. There is an alternate method. Hint : if all permutations were here, how many times would A appear in each position ? What is the parity of this number ? <pre>ABCD

Find the missing permutation (view source)