Solution to level 13 in Untrusted: http://alex.nisnevich.com/untrusted/

untrusted-lvl13-solution.js

/*
 * robotMaze.js
 *
 * The blue key is inside a labyrinth, and extracting
 * it will not be easy.
 *
 * It's a good thing that you're a AI expert, or
 * we would have to leave empty-handed.
 */

function startLevel(map) {
    map.getRandomInt = function(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min;
    }

    map.placePlayer(map.getWidth()-1, map.getHeight()-1);
    var player = map.getPlayer();

    map.defineObject('robot', {
        'type': 'dynamic',
        'symbol': 'R',
        'color': 'gray',
        'onCollision': function (player, me) {
            me.giveItemTo(player, 'blueKey');
        },
        'behavior': function (me) {
    
if (me.heat == undefined)
{
	me.heat = [];
	for (var i = 0; i < map.getWidth(); ++i)
	{
    	me.heat[i] = new Array(map.getHeight());
		for (var j = 0; j < map.getHeight(); ++j)
		{
			me.heat[i][j] = -255;
		}
	}
	
	me.heat[map.getWidth() - 2][8] = 0;
	me.heat[map.getWidth() - 2][9] = -1;
	me.heat[map.getWidth() - 2][10] = -2;
	
	var stak = [[map.getWidth() - 2, 8]];
	
	do
	{
		var coords = stak.pop();
        var newheat = me.heat[coords[0]][coords[1]] + 1;
        var moves = map.getAdjacentEmptyCells(coords[0], coords[1]);
        
		for (var i = 0; i < moves.length; ++i) {

        	var move = moves[i];

			if (me.heat[move[0][0]][move[0][1]] == -255)
			{

				me.heat[move[0][0]][move[0][1]] = newheat;
                
				stak.push([move[0][0], move[0][1]]);
                
                var color = newheat.toString(16);
                if (color.length == 1)
                {
                	color += '00';
                }
                else
                {
                	color += '0';
                }
                
                map.setSquareColor(move[0][0], move[0][1], '#' + 
                color);
                
			}
		}
	} while (stak.length != 0);
}
else
{
	if (me.getX() == map.getWidth() - 2 && me.getY() > 6)
    {
    	me.move('down');
    }
    else
    {
	var minheat = 255;
	var whichmove = null;
	var moves = map.getAdjacentEmptyCells(me.getX(), me.getY());
	moves.forEach(function(move) {
		if (me.heat[move[0][0]][move[0][1]] < minheat)
		{
			minheat = me.heat[move[0][0]][move[0][1]];
			whichmove = move;
		}
	});
	me.move(whichmove[1]);
    }
}
            
            // move randomly
            //var moves = map.getAdjacentEmptyCells(me.getX(), me.getY());
            // getAdjacentEmptyCells gives array of ((x, y), direction) pairs
            //me.move(moves[map.getRandomInt(0, moves.length - 1)][1]);
            
            
            











































        }
    });

    map.defineObject('barrier', {
        'symbol': '░',
        'color': 'purple',
        'impassable': true,
        'passableFor': ['robot']
    });

    map.placeObject(0, map.getHeight() - 1, 'exit');
    map.placeObject(1, 1, 'robot');
    map.placeObject(map.getWidth() - 2, 8, 'blueKey');
    map.placeObject(map.getWidth() - 2, 9, 'barrier');

    var autoGeneratedMaze = new ROT.Map.DividedMaze(map.getWidth(), 10);
    autoGeneratedMaze.create( function (x, y, mapValue) {
        // don't write maze over robot or barrier
        if ((x == 1 && y == 1) || (x == map.getWidth() - 2 && y >= 8)) {
            return 0;
        } else if (mapValue === 1) { //0 is empty space 1 is wall
            map.placeObject(x,y, 'block');
        } else {
            map.placeObject(x,y,'empty');
        }
    });
}

function validateLevel(map) {
    map.validateExactlyXManyObjects(1, 'exit');
    map.validateExactlyXManyObjects(1, 'robot');
    map.validateAtMostXObjects(1, 'blueKey');
}

function onExit(map) {
    if (!map.getPlayer().hasItem('blueKey')) {
        map.writeStatus("We need to get that key!");
        return false;
    } else {
        return true;
    }
}