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"

class Solution {
    public String simplifyPath(String path) {
        String[] strs = path.split("/");
        ArrayList<String> list1 = new ArrayList<String>();
        for(int i = 0; i < strs.length; i++){
        //将空字符串（由类似这种"/a//c"的字符串产生）和 "." （"."代表当前目录不影响路径）去掉，保存到 list1
        if (strs[i].isEmpty() || strs[i].equals(".")) {
            continue;
        }
        list1.add(strs[i]);
        }
        ArrayList<String> list2 = new ArrayList<String>();
        for(int i = 0; i < list1.size(); i++){
            if(list1.get(i).equals("..")){
                if(!list2.isEmpty()){
                    list2.remove(list2.size() - 1);
                }
            } else list2.add(list1.get(i));
        }
        String res = String.join("/",list2);
        res = "/" + res;
        return res;
    }
}

这种题真是索然无味

https://leetcode.wang/leetCode-71-Simplify-Path.html

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"

题意

简化绝对路径，最后一个目录后不能有/

空路径写作"/"，如果要求访问根目录的上一级目录则自动简化为根目录自己，如例2

题解

 1 class Solution {
 2 public:
 3     string simplifyPath(string path) {
 4         string ans = "";
 5         int p = 0,l = path.length();
 6         while (p < l) {
 7             if (path[p] != ‘/‘) {
 8                 string menu = "";
 9                 while (p < l&&path[p] != ‘/‘)
10                     menu += path[p++];
11                 if (menu == ".")
12                     continue;
13                 else if (menu == "..") {
14                     int idx = ans.rfind(‘/‘);
15                     if (idx == string::npos)continue;
16                     ans.erase(idx);
17                 }
18                 else
19                     ans += "/" + menu;
20             }
21             p++;
22         }
23         if (ans.empty())return "/";
24         return ans;
25     }
26 };