Good day,
I am working on a text-based games written in Javascript. I have variable named map
that is an associating object containing another object for each rooms. I have found a little algorithm somewhere and I am not sure how to modify it for my specific task.
My variable:
/** * [003]-[004] * | | * [001]-[002] [007] * | | * [005]-[006] **/ var map = { "001" : { "Id" : "001", "Name" : "Room 001", "Directions" : { "N" : "", "S" : "", "E" : "002", "W" : "" } }, "002" : { "Id" : "002", "Name" : "Room 002", "Directions" : { "N" : "003", "S" : "005", "E" : "", "W" : "001" } }, "003" : { "Id" : "003", "Name" : "Room 003", "Directions" : { "N" : "", "S" : "002", "E" : "004", "W" : "" } }, "004" : { "Id" : "004", "Name" : "Room 004", "Directions" : { "N" : "", "S" : "007", "E" : "", "W" : "003" } }, "005" : { "Id" : "005", "Name" : "Room 005", "Directions" : { "N" : "002", "S" : "", "E" : "006", "W" : "" } }, "006" : { "Id" : "006", "Name" : "Room 006", "Directions" : { "N" : "007", "S" : "", "E" : "", "W" : "005" } }, "007" : { "Id" : "007", "Name" : "Room 007", "Directions" : { "N" : "004", "S" : "006", "E" : "", "W" : "" } } }; function findSteps( id, map, array ) { if ( ! ( map && "object" === typeof map ) ) { return; } if ( map.Id === id ) { return map; } for ( var x in map ) { if ( Object.hasOwnProperty.call( map, x ) ) { map.Id && array.push( map.Id ); //used to exclude undefined var result = findSteps( id, map[ x ], array ); if ( result !== undefined ) { return [ result, array ]; } } } } console.dir( findSteps( "004", map, [] ) ); // Actually returns [objectObject],001,001,001,002,002,002,003,003,003
I would like the function to return an array of array with all the possible paths that I will later iterate to find the closest available path.
The desired result would be something like:
output = [ [ "001", "002", "003", "004" ], [ "001", "002", "005", "006", "007", "004" ] ]
The function should also accept a startup Id
. I am thinking about something that would stop the recursivity if nothing have been found before "map.length"n
iterations.
Maybe a little hint would be also appreciated.
Thank you!
PS: I have looked at a few Q/A founds on SO about recursive object search, this is exactly where I found the function I am using.
Edit:
After much thinking, and hopefully I won’t be wrong on that. I believe I only need THE shortest path.
Edit:
http://jsfiddle.net/GxZYX/1/ here is my test of implementing breadth first search. (bugged)
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Answer
To find the shortest path between two nodes in an unwheight graph like yours you just need to do a Breadth-first-search.
function linkedPathToList(next, node){ var path = []; while(true){ path.push(node); if(node == next[node]) break; node = next[node]; } return path; } var breadthFirstSearch = function( map, startRoomId, endRoomId ) { var next = {}; next[endRoomId] = endRoomId; var currentLevel = [ map[endRoomId] ]; //(the traditional version of the algorithm uses a queue instead of the // complicated two-array thing though) while( currentLevel.length ) { //if curr level is nodes at distance d from the end //next level is d+1 var nextLevel = []; for(var i=0; i<currentLevel.length; i++) { var node = currentLevel[i]; if ( node.Id == startRoomId ) { return linkedPathToList(next, startRoomId); } for( var direction in node.Directions ) { var neighbor = node.Directions[direction]; if( !next[neighbor] ) { next[neighbor] = node.Id; nextLevel.push( map[neighbor] ); } } } currentLevel = nextLevel; } return null; }; var map = { "001" : { "Id" : "001", "Name" : "Room 001", "Directions" : { "E" : "002" } }, "002" : { "Id" : "002", "Name" : "Room 002", "Directions" : { "N" : "003", "S" : "005", "W" : "001" } }, "003" : { "Id" : "003", "Name" : "Room 003", "Directions" : { "S" : "002", "E" : "004" } }, "004" : { "Id" : "004", "Name" : "Room 004", "Directions" : { "S" : "007", "W" : "003" } }, "005" : { "Id" : "005", "Name" : "Room 005", "Directions" : { "N" : "002", "E" : "006" } }, "006" : { "Id" : "006", "Name" : "Room 006", "Directions" : { "N" : "007", "W" : "005" } }, "007" : { "Id" : "007", "Name" : "Room 007", "Directions" : { "N" : "004", "S" : "006" } } }; console.log('shortest path', breadthFirstSearch( map, "001", "004" ) );