Created
March 28, 2014 21:24
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Towers of hanoi
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| var _ = require("underscore"); | |
| function hanoi(numPieces) { | |
| var stacks = [ _.range(1, numPieces + 1).reverse(), [], [] ]; | |
| function findOtherStackNo(one, two) { | |
| return _.without([0, 1, 2], one, two)[0]; | |
| } | |
| function peek(stack) { | |
| return _.last(stack); | |
| } | |
| function pieceAbove(piece, stack) { | |
| var ind = _.indexOf(stack, piece); | |
| return stack[ind + 1]; | |
| } | |
| //on which stack is it? | |
| function findPiece(piece) { | |
| return _.find([0, 1, 2], function (stackNo) { | |
| return _.contains(stacks[stackNo], piece); | |
| }) | |
| } | |
| function movePiece(piece, sourceNo, targetNo) { | |
| sourceNo = sourceNo || findPiece(piece); | |
| var source = stacks[sourceNo], | |
| target = stacks[targetNo], | |
| otherNo = findOtherStackNo(sourceNo, targetNo); | |
| if (peek(source) !== piece) { | |
| if( allAbove(piece, sourceNo).length < 3){ | |
| movePiece(pieceAbove(piece, source), sourceNo, otherNo); | |
| } else{ | |
| moveAllAbove(piece, sourceNo, otherNo); | |
| } | |
| } | |
| if( peek(target) < piece){ | |
| movePiece( peek(target), targetNo, otherNo); | |
| } | |
| target.push(source.pop()); | |
| printIt(); | |
| } | |
| //all pieces above the specified piece on the specified stack | |
| function allAbove(piece, sourceNo) { | |
| var ind = _.indexOf( stacks[sourceNo], piece); | |
| return _.rest( stacks[sourceNo], ind + 1); | |
| } | |
| function moveAllAbove(piece, sourceNo, targetNo) { | |
| moveAll( allAbove(piece, sourceNo), targetNo); | |
| } | |
| function moveAll(pieces, targetNo) { | |
| _.each(pieces, function (piece) { | |
| movePiece(piece, null, targetNo); | |
| }); | |
| } | |
| function strPos(pos, stack) { | |
| var value = stack[pos]; | |
| if (value) { | |
| return _.map( _.range(value),function () { return "_";}).join(""); | |
| } | |
| return "|"; | |
| } | |
| function printIt() { | |
| console.log(); | |
| _.each( _.range(numPieces).reverse(), function (pos) { | |
| console.log(strPos(pos, stacks[0]) + "\t" + strPos(pos, stacks[1]) + "\t" + strPos(pos, stacks[2])); | |
| }); | |
| console.log("\n================================\n"); | |
| } | |
| //gogogo | |
| (function () { | |
| printIt(); | |
| moveAll(_.range(1, numPieces + 1).reverse(), 2); | |
| })(); | |
| } | |
| hanoi(5); |
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