Simplify Path

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

难度：medium

public class Solution {
    public String simplifyPath(String path) {
        StringBuilder res = new StringBuilder();
        String[] tempRes = path.split("/");
        List<String> tokens = new ArrayList<>();
        for(String str : tempRes) {
            if(str.equals(".") || str.equals("")) {
                continue;
            }
            if(str.equals("..")) {
                if(!tokens.isEmpty()) {
                    tokens.remove(tokens.size() - 1);
                }
            } else {
                tokens.add(str);
            }
        }
        if(tokens.isEmpty()) {
            return "/";
        }
        for(String str : tokens) {
            res.append("/");
            res.append(str);
        }
        return res.toString();
    }
}