71. Simplify Path

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Problem

Given an absolute path for a file (Unix-style), simplify it.

For example, path = “/home/”, => “/home” path = “/a/./b/../../c/”, => “/c” path = “/a/../../b/../c//.//”, => “/c” path = “/a//b////c/d//././/..”, => “/a/b/c”

In a UNIX-style file system, a period (‘.’) refers to the current directory, so it can be ignored in a simplified path. Additionally, a double period (“..”) moves up a directory, so it cancels out whatever the last directory was. For more information, look here: https://en.wikipedia.org/wiki/Path_(computing)#Unix_style

Corner Cases:

Did you consider the case where path = “/../”? In this case, you should return “/”. Another corner case is the path might contain multiple slashes ‘/’ together, such as “/home//foo/”. In this case, you should ignore redundant slashes and return “/home/foo”.

Code

class Solution {
    public String simplifyPath(String path) {
        Stack<String> stack = new Stack<>();
        String[] arr = path.split("/");

        for(int i = 0; i < arr.length; i++){
            String curr = arr[i].trim();
            if(curr == null || curr.length() == 0 || curr.equals(".")) continue;

            if(curr.equals("..")){
                if(!stack.isEmpty()){
                    stack.pop();
                }
            } else {
                stack.push(curr);
            }
        }

        String res = "";

        while(!stack.isEmpty()){
            res = "/" + stack.pop() + res;
        }

        return res.length() == 0 ? "/" : res;
    }
}