Codewars: Path Finder

Question

Task

You are at position [0, 0] in maze NxN and you can only move in one of the four cardinal directions (i.e. North, East, South, West). Return true if you can reach position [N-1, N-1] or false otherwise.

• Empty positions are marked ..
• Walls are marked W.
• Start and exit positions are empty in all test cases.

I know this exist already, but my solution is a bit different, so...

It is very cool and i see that people struggle a lot because of performance (tests are big). I had 3 problems here:

1. How to make recursion stop after finding solution
2. Before adding "visited" array, i modificated maze array on each turn: maze = maze.slice(0, pos) + 'p' + maze.slice(pos + 1). Adding space complexity ("visited" array) SOLVED A LOT.
3. Converting [x, y] <=> userPosition, as initially maze is by pure string. I found out that it's not even needed to do this convert (division, modulus). Does this improvement means something?

Solution:

"use strict";
function pathFinder(maze) {
 const size = maze.split("\n")[0].length;
 const visited = new Array((size + 1) * size);
 return solveMaze(maze, visited, size, 0);
}
function solveMaze(maze, visited, size, userPosition){
 
 if (userPosition === maze.length - 1) {
 return true;
 } else {
 
 let result;
 visited[userPosition] = true;
 
 const allSteps = [userPosition - (size + 1), //up
 userPosition + 1, //right
 userPosition + (size + 1), //down
 userPosition - 1]; //left
 const possibleSteps = allSteps.filter(pos => pos > 0 && 
 pos < maze.length && 
 maze[pos] !== 'W' && 
 !visited[pos] && 
 maze[pos] !== '\n');
 
 for (const step of possibleSteps) {
 result = solveMaze(maze, visited, size, step);
 if (result) return result;
 }
 return false;
 }
}

• radarbob: if(userPosition...) { return true } else { ...} The "hard return" makes "else" unnecessary. Just let code fall through. That final return false - instead: return result because Hard coding "false" potentially masks bugs; or creates them.
• Михаил Спирин: thanks very much! I understand. My approach here was that recursion === base case => recursive case order, but definitely this can be changed to make code cleaner.