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) {
            if (me.isLastStepDeadEnd == undefined) 
            	me.isLastStepDeadEnd = false;
            if (me.lastCoords == undefined) me.lastCoords = getCoordAsAry();
            if (me.deadEnds == undefined) me.deadEnds = [];
            if (me.freeWay == undefined) me.freeWay = [];
            if (me.foundKey == undefined) me.foundKey = false;
            
            if (map.getObjectTypeAt(me.getX() + 1, me.getY()) == 'blueKey') {
            	me.move('right');
                me.foundKey = true;
            } else if (me.foundKey) {
            	me.move('down');
            }
            
            if (!isRobotInDeadEnd()) {
                me.freeWay.push(getCoordAsAry());
                map.setSquareColor(getCoordAsAry()[0], 
                	getCoordAsAry()[1], 'green');
                var move = getActualMoves()[0];
                me.move(move[1]);
            } else {             
            	me.deadEnds.push(getCoordAsAry());
                map.setSquareColor(getCoordAsAry()[0], 
                    	getCoordAsAry()[1], 'red');
                var move = getActualMoves()[0];
                me.move(move[1]);
            }
            
            function getCoordAsAry() {
            	return [me.getX(), me.getY()];
            }
            
            function isThereDeadEnd(x, y, way) {
                var contain = false;
                if (way == undefined) way = me.deadEnds;
                else way = me.freeWay
                way.forEach(function(end) {
                	if (end[0] == x && end[1] == y)
                    	contain = true;
                });
                return contain;
            }
            
            function isRobotInDeadEnd() {
            	var moves = getMoves();
                var actualMoves = 0;
                moves.forEach(function(move) {
                	if (!isThereDeadEnd(move[0][0], move[0][1]))
                    	actualMoves++;
                });
                return actualMoves == 1;
            }
            
            function getActualMoves() {
                var moves = getMoves();
                var actualMoves = [];
                moves.forEach(function(move) {
                	if (!isThereDeadEnd(move[0][0], move[0][1]))
                    	if (!isThereDeadEnd(move[0][0], 
                        	move[0][1], true)
                           )
                        	actualMoves.unshift(move);
                        else
                    		actualMoves.push(move);
                         
                });
                return actualMoves;
            }
            
            function howManyMoves() {
				return getMoves().length;
            }
            
            function getMoves() {
            	return map.getAdjacentEmptyCells(me.getX(), me.getY());
            }
        }
    });

    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;
    }
}