0071. Simplify Path.js

// Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.

// In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix
// Note that the returned canonical path must always begin with a slash /, and there must be only a single slash / between two directory names. The last directory name (if it exists) must not end with a trailing /. Also, the canonical path must be the shortest string representing the absolute path. 

// Example 1:

// Input: "/home/"
// Output: "/home"
// Explanation: Note that there is no trailing slash after the last directory name.

// Example 2:

// Input: "/../"
// Output: "/"
// Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.

// Example 3:

// Input: "/home//foo/"
// Output: "/home/foo"
// Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.

// Example 4:

// Input: "/a/./b/../../c/"
// Output: "/c"

// Example 5:

// Input: "/a/../../b/../c//.//"
// Output: "/c"

// Example 6:

// Input: "/a//b////c/d//././/.."
// Output: "/a/b/c"


// 1) 字符串转数组
/**
 * @param {string} path
 * @return {string}
 */
const simplifyPath = (path) => {
  let arr = path.split('/')  
  let res = []
  for (let i = 0; i < arr.length; i++) {
    let p = arr[i]
    if (p === '..') {
      res.pop()
    } else if (p !== '' && p !== '.') {
      res.push(p)
    }
  }
  return '/' + res.join('/')
}
// Runtime: 64 ms, faster than 69.64% of JavaScript online submissions for Simplify Path.
// Memory Usage: 35.7 MB, less than 66.67% of JavaScript online submissions for Simplify Path.