dungeonBlaster.js

// passing 100% of tests
function getStartPosition(m) {
 let position = '';
 m.forEach((row, x) => {
  const cells = row.split('');
  const y = cells.indexOf('*');
  if (y !== -1) {
   position += x + ',';
   position += y;
  }
 }); 
 return position;
}

const getOutOfBoundsTile = ({ x, y, move, m }) => {
 let pos;
 
 // moving up
 if (move[0] === -1 && move[1] === 0) {  
  pos = `${m.length - 1},${y + move[1]}`;
 } 
 
 // moving right
 if (move[0] === 0 && move[1] === 1) {  
  pos = `${x + move[0]},${0}`;
 }
 
 // moving down
 if (move[0] === 1 && move[1] === 0) {  
  pos = `${0},${y + move[1]}`;
 }
 
 // moving left
 if (move[0] === 0 && move[1] === -1) {  
  pos = `${x + move[0]},${m[x].length - 1}`;
 }
 
 return pos;
};

const removeItemFromMap = ({m, board, pos}) => {
 return m.map((row) => {
  if (row.indexOf(board.history[pos].tile) >= 0) {
   return row.replace(board.history[pos].tile, ' ');
  }
  return row;
 });
};

function explore(m, board, character) {
 if (character.foundExit) {
  return;
 }
 
 const validTile = /[\s|a-z|*]/; 
 const currentPos = character.currentPosition.split(',');
 const x = currentPos[0];
 const y = currentPos[1];
 
 // visit all other possible tiles
 const adjacentTiles = [[-1, 0], [0, 1], [1, 0], [0, -1]];
 adjacentTiles.forEach((move) => {
  let pos = `${+x + move[0]},${+y + move[1]}`;
  if (!board.history[pos]) {
   pos = getOutOfBoundsTile({ x: +x, y: +y, m, move });
  }   
  
  // if encountering a valid tile
  if (board.history[pos] && validTile.test(board.history[pos].tile) && board.history[pos].visited === 0) {   
   // if encountering a key
   if (board.history[pos] && /[a-z]/.test(board.history[pos].tile)) {
    // remove the key
    m = removeItemFromMap({ m, board, pos });
    
    // store the key
    character.keys.push(board.history[pos].tile.toUpperCase());
    
    // reset the board
    board = new Board(m, {});
   }
   
   // visit the tile and start a new node
   board.history[pos].visited += 1;   
   character.currentPosition = pos;
   return explore(m, new Board(m, board.history), character);
  }
  
  // if encountering a door
  if (board.history[pos] && /[A-Z]/.test(board.history[pos].tile)) {
   // check for key
   if (character.keys.indexOf(board.history[pos].tile) >= 0) {
    board.history[pos].visited += 1;
    character.currentPosition = pos;
    m = removeItemFromMap({ m, board, pos });
    return explore(m, new Board(m, board.history), character);
   } 
  }
  
  // if encountering the exit
  if (board.history[pos] && board.history[pos].tile === '^') {
   character.foundExit = true;
   return;
  }  
 });
}

function Board(m, history) {
 this.history = history;
 m.forEach((row, x) => {
  row.split('').forEach((cell, y) => {
   const key = `${x},${y}`;
   this.history[key] = {
    tile: cell,
    visited: history[key] && history[key].visited === 1 ? 1 : 0,
   };
  });
 });
}

function dungeonBlaster(m) {
 const character = {
  currentPosition: getStartPosition(m),
  foundExit: false,
  keys: [],
 };

 // make the first move...
 explore(m, new Board(m, {}), character);
 
 if (character.foundExit) {
  return true;
 }
 
 return false;
}