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) {
            // 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]);

            var rightFrom = {
               'right':'down',
               'down':'left',
               'left':'up',
               'up':'right'
            };
            var leftFrom = {
               'right':'up',
               'up':'left',
               'left':'down',
               'down':'right'
            };
            me.forward = me.forward || 'right';
            me.history = me.history || {};
            
            // If we've been in this exact location, facing
            // the exact same way, then try to mix things up
            // a bit.
            var key = me.forward + "," + me.getX() + "," + me.getY();
            
            if (me.history[key]) {
              me.forward = leftFrom[me.forward];
              me.history[key] = true;
              return;
            }
            me.history[key] = true;
            
            // If we can't go forward, change forward and start over.
            if (me.canMove(rightFrom[me.forward])) {
              me.forward = rightFrom[me.forward];
              me.move(me.forward);
            }
            else if(!me.canMove(me.forward)) {
              me.forward = rightFrom[me.forward];
            }
            else {
              me.move(me.forward);
            }
            
            






































        }
    });

    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;
    }
}