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 (typeof(me.mapSquareColors) == "undefined") {
  var currentSet = map.getAdjacentEmptyCells(map.getWidth() - 2, 8);
  //currentSet = new Set(currentSet);
  
  var currentColor = 0xFFD700; // gold
  
  me.mapSquareColors = new Array(map.getWidth());
  for (x = 0; x < map.getWidth(); x++) {
    me.mapSquareColors[x] = new Array(map.getHeight());
  }
  
  while (me.mapSquareColors[me.getX()][me.getY()] == undefined) {
    currentColor -= 2;
    var newSet = []
    for (i = 0; i < currentSet.length; i++) {
      var move = currentSet[i];
      var coordinates = move[0];
      var x = coordinates[0];
      var y = coordinates[1];
      var colorString = "#" + currentColor.toString(16);
      
      if (me.mapSquareColors[x][y] == undefined) {
        map.setSquareColor(x, y, colorString);
        me.mapSquareColors[x][y] = colorString;
        var newMoves = map.getAdjacentEmptyCells(x, y);
        for (j = 0; j < newMoves.length; j++) {
          move = newMoves[j];
          newSet.push(move);
        }
      }
     
    }
    currentSet = newSet;
  }
} else {
  var moves = map.getAdjacentEmptyCells(me.getX(), me.getY())
  console.log(["Turn 2: ", moves]);
  var bestColor = me.mapSquareColors[me.getX()][me.getY()];
  var bestMove = "down";
  for (i = 0; i < moves.length; i++) {
    var move = moves[i];
    var x = move[0][0];
    var y = move[0][1];
    if (me.mapSquareColors[x][y] > bestColor) {
      bestColor = me.mapSquareColors[x][y];
      bestMove = move[1];
    }
  }
  me.move(bestMove);
}

        }
    });

    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;
    }
}