0071-simplify-path.js

/**
 * 71. Simplify Path
 * https://leetcode.com/problems/simplify-path/
 * Difficulty: Medium
 *
 * You are given an absolute path for a Unix-style file system, which always begins
 * with a slash '/'. Your task is to transform this absolute path into its simplified
 * canonical path.
 *
 * The rules of a Unix-style file system are as follows:
 * - A single period '.' represents the current directory.
 * - A double period '..' represents the previous/parent directory.
 * - Multiple consecutive slashes such as '//' and '///' are treated as a single slash '/'.
 * - Any sequence of periods that does not match the rules above should be treated as a
 *   valid directory or file name. For example, '...' and '....' are valid directory or
 *   file names.
 *
 * The simplified canonical path should follow these rules:
 * - The path must start with a single slash '/'.
 * - Directories within the path must be separated by exactly one slash '/'.
 * - The path must not end with a slash '/', unless it is the root directory.
 * - The path must not have any single or double periods ('.' and '..') used to denote
 *   current or parent directories.
 *
 * Return the simplified canonical path.
 */

/**
 * @param {string} path
 * @return {string}
 */
var simplifyPath = function(path) {
  const stack = [];
  for (const segment of path.split('/')) {
    if (segment === '.' || segment === '') continue;
    if (segment === '..') stack.pop();
    else stack.push(segment);
  }
  return `/${stack.join('/')}`;
};