Training on Warcraft Series I

solution.js

function generateEmptyPathArray(pathLength) {
  let path = ["M"];
  for (let i = 1; i < pathLength-1; i++) {
    path.push(".");
  }
  path.push("B");
  return path;
}

function simulateMining(path, time) {
	const LEN = path.length;
  const workers = [];

  // Put default state of workers in our workers array.
	for (let i = 0; i < LEN; i++) {
    const action = path.charAt(i);
    if (action === "<" || action === ">") {
      let direction = "L"; 
      if (action === ">") {
        direction = "R";
      }
      workers.push([i, action, direction]);
    }
  }

  // If no workers, just return the "path" string N times (where N="time").
  if (!workers.length) {
    return new Array(time).fill(path);
  }

  const finalPaths = [path];

  for (let i = 1; i < time; i++) {
    let nextPath = generateEmptyPathArray(LEN);

    for (let w = 0; w < workers.length; w++) {
      const [index, action, direction] = workers[w];

      let nextIndex = undefined;
      let nextAction = action;
      let nextDirection = direction;

      if (action === "<") {
        nextIndex = index - 1;
      } else if (action === ">") {
        nextIndex = index + 1;
      } else if (action === "#" || action === "*") {
        // assume we were heading left..
        nextIndex = index - 1;
        nextAction = "<";
        if (direction === "R") {
          nextIndex = index + 1;
          nextAction = ">";
        }
      }

      let nextMove = nextPath[nextIndex];

      if (nextMove === "M" || nextMove === "B") {
        nextAction = "*";
        nextDirection = direction === "R" ? "L" : "R";
      } else if (nextMove === ">" || nextMove === "<") { // Someone is already there...
        nextAction = "#";
      } 

      nextPath[nextIndex] = nextAction;
      workers[w] = [nextIndex, nextAction, nextDirection];
    }

    finalPaths.push(nextPath.join(""));
  }

	return finalPaths;
}