Created
January 23, 2015 01:30
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// source http://jsbin.com/juzohunafe
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>JS Bin</title> | |
| </head> | |
| <body> | |
| <script id="jsbin-javascript"> | |
| function insertNumberAtEachIndex(a, xs) { | |
| console.log("insertNumberAtEachIndex(" + a + ", " + JSON.stringify(xs) + ") =>"); | |
| var insertions = xs.map(function (x, i, xs) { | |
| var insertion = [].concat(xs); | |
| insertion.splice(i,0,a); | |
| return insertion; | |
| }); | |
| var lastInsertion = [].concat(xs); | |
| lastInsertion.push(a); | |
| insertions.push(lastInsertion); | |
| console.info(insertions); | |
| return insertions; | |
| } | |
| insertNumberAtEachIndex(1, [2,3]); | |
| insertNumberAtEachIndex(1, [2,3,4]); | |
| function getPermutations(xs) { | |
| console.log("getPermutations(" + JSON.stringify(xs) + ") =>"); | |
| var head | |
| , tail | |
| , tailPermutations | |
| , permutations | |
| , result | |
| ; | |
| if(xs.length === 0) { | |
| result = []; | |
| } | |
| else if(xs.length === 1) { | |
| result = [xs]; | |
| } | |
| else if(xs.length === 2) { | |
| result = [[xs[0],xs[1]],[xs[1],xs[0]]]; | |
| } | |
| else if(xs.length > 2) { | |
| head = xs[0]; | |
| tail = xs.slice(1); | |
| tailPermutations = getPermutations(tail); | |
| permutations = tailPermutations.reduce(function (a, ps) { | |
| var permutations2 = insertNumberAtEachIndex(head, ps); | |
| return a.concat(permutations2); | |
| }, []); | |
| result = permutations; | |
| } | |
| console.log(result); | |
| return result; | |
| } | |
| getPermutations([1]); | |
| getPermutations([1,2]); | |
| getPermutations([1,2,3]); | |
| getPermutations([1,2,3,4]); | |
| </script> | |
| <script id="jsbin-source-javascript" type="text/javascript">function insertNumberAtEachIndex(a, xs) { | |
| console.log("insertNumberAtEachIndex(" + a + ", " + JSON.stringify(xs) + ") =>"); | |
| var insertions = xs.map(function (x, i, xs) { | |
| var insertion = [].concat(xs); | |
| insertion.splice(i,0,a); | |
| return insertion; | |
| }); | |
| var lastInsertion = [].concat(xs); | |
| lastInsertion.push(a); | |
| insertions.push(lastInsertion); | |
| console.info(insertions); | |
| return insertions; | |
| } | |
| insertNumberAtEachIndex(1, [2,3]); | |
| insertNumberAtEachIndex(1, [2,3,4]); | |
| function getPermutations(xs) { | |
| console.log("getPermutations(" + JSON.stringify(xs) + ") =>"); | |
| var head | |
| , tail | |
| , tailPermutations | |
| , permutations | |
| , result | |
| ; | |
| if(xs.length === 0) { | |
| result = []; | |
| } | |
| else if(xs.length === 1) { | |
| result = [xs]; | |
| } | |
| else if(xs.length === 2) { | |
| result = [[xs[0],xs[1]],[xs[1],xs[0]]]; | |
| } | |
| else if(xs.length > 2) { | |
| head = xs[0]; | |
| tail = xs.slice(1); | |
| tailPermutations = getPermutations(tail); | |
| permutations = tailPermutations.reduce(function (a, ps) { | |
| var permutations2 = insertNumberAtEachIndex(head, ps); | |
| return a.concat(permutations2); | |
| }, []); | |
| result = permutations; | |
| } | |
| console.log(result); | |
| return result; | |
| } | |
| getPermutations([1]); | |
| getPermutations([1,2]); | |
| getPermutations([1,2,3]); | |
| getPermutations([1,2,3,4]); | |
| </script></body> | |
| </html> |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| function insertNumberAtEachIndex(a, xs) { | |
| console.log("insertNumberAtEachIndex(" + a + ", " + JSON.stringify(xs) + ") =>"); | |
| var insertions = xs.map(function (x, i, xs) { | |
| var insertion = [].concat(xs); | |
| insertion.splice(i,0,a); | |
| return insertion; | |
| }); | |
| var lastInsertion = [].concat(xs); | |
| lastInsertion.push(a); | |
| insertions.push(lastInsertion); | |
| console.info(insertions); | |
| return insertions; | |
| } | |
| insertNumberAtEachIndex(1, [2,3]); | |
| insertNumberAtEachIndex(1, [2,3,4]); | |
| function getPermutations(xs) { | |
| console.log("getPermutations(" + JSON.stringify(xs) + ") =>"); | |
| var head | |
| , tail | |
| , tailPermutations | |
| , permutations | |
| , result | |
| ; | |
| if(xs.length === 0) { | |
| result = []; | |
| } | |
| else if(xs.length === 1) { | |
| result = [xs]; | |
| } | |
| else if(xs.length === 2) { | |
| result = [[xs[0],xs[1]],[xs[1],xs[0]]]; | |
| } | |
| else if(xs.length > 2) { | |
| head = xs[0]; | |
| tail = xs.slice(1); | |
| tailPermutations = getPermutations(tail); | |
| permutations = tailPermutations.reduce(function (a, ps) { | |
| var permutations2 = insertNumberAtEachIndex(head, ps); | |
| return a.concat(permutations2); | |
| }, []); | |
| result = permutations; | |
| } | |
| console.log(result); | |
| return result; | |
| } | |
| getPermutations([1]); | |
| getPermutations([1,2]); | |
| getPermutations([1,2,3]); | |
| getPermutations([1,2,3,4]); |
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