permutation-rank ================ Ranks and unranks permutations. Based on the following paper: W. Myrvold, F. Ruskey. (2000) "[Ranking and Unranking Permutations in Linear Time](http://webhome.cs.uvic.ca/~ruskey/Publications/RankPerm/RankPerm.html)". Information Processing Letters. Usage ===== First install using npm: npm install permutation-rank Then you can use it like this: ```javascript var prank = require("permutation-rank") var perm = [0,3,1,2] var r = prank.rank(perm) console.log("r = ", r) var u = prank.unrank(perm.length, r) console.log("u = ", u) //Prints: // r = 15 // u = [ 0, 3, 1, 2 ] ``` `prank.rank(permutation)` ----------------------------------------------- Computes an integer representing the colexicographic rank of the permutation * `permutation` is an array encoding some permutation **Returns** An integer representing the ranked encoding of the permutation `prank.unrank(length, rank[, result])` -------------------------------------------------- Computes a permutation from a rank order with the given length * `length` is the length of the permuation * `rank` is the index of the permutation * `result` is an optional argument which stores the result of the inversion **Returns** The permutation at the given rank Credits ======= (c) 2013 Mikola Lysenko. MIT License