71. Simplify Path

Given an absolute path for a file (Unix-style), simplify it. For example, path = "/home/", => "/home" path = "/a/./b/../../c/", => "/c"

题意：

"."表示当前目录； ".."表示上级目录

class Solution {
    public String simplifyPath(String path) {
       ArrayDeque<String> stack = new ArrayDeque<>();
        String []sum = path.split("/");
        for (int i = 0; i < sum.length; i++) 
            if(!sum[i].equals("") && sum[i].equals("..") && !stack.isEmpty())
                stack.pop();
            else if(!sum[i].equals("") && !sum[i].equals(".") && !sum[i].equals(".."))
                stack.push(sum[i]);

        String value="";
        if(stack.isEmpty())
            value = "/";
        while(!stack.isEmpty()) {
            value = "/"+stack.pop()+value;
        }

        return value;
    }
}