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) {
    // Hint: you can press R or 5 to "rest" and not move the
    // player, while the robot moves around.

    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) {
            // last steps first
            if(me.getX() == 48 && me.getY() == 8) 
            {
            	me.move("down");
                return;
            }
         
            
            
            
            // create and init visited map
            visited=[];
			for (i=0; i < 100; i++) {
				visited[i]=new Array(100);
                for(j=0; j<100; j++)
                	visited[i][j] = 0;
            }
            
            // init frontier
            var frontier = new Array();
            frontier.push([48, 8], [47,8]);
            
            for(i=0; i<frontier.length; i++) {
            	var x = frontier[i][0];
                var y = frontier[i][1];
            	map.setSquareColor(x, y, "#f00");
                // make cell visited
                visited[x][y] = 1;
                // get free cell neighbours
                var neigh = map.getAdjacentEmptyCells(x,y);
                for(j=0; j<neigh.length; j++) {
                	var nx = neigh[j][0][0];
                    var ny = neigh[j][0][1];
                    
					if(nx == me.getX() && ny == me.getY()) {
                    	var t = {"left": "right", "right": "left",
                        	"up": "down", "down": "up"};
                        me.move(t[neigh[j][1]]);
                        return;
                    }
                    
                    if(visited[nx][ny] == 0)
                    	frontier.push([nx, ny]);
                }
            }
            
            
            // 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;
    }
}