看leetcode一个题很好的解答 Simplify Path

其实理解题意比较困难，因很多corner case都不清楚
For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"
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".
题目就这些case，其实没有说清楚是遇到"/../"其实只退一层，遇到"."也不退，只是不显示这一层而已，用stack就可以解决这题
用"/"可以把string 分成很多份，如果最后是空的，就返回"/"

public String simplifyPath(String path) {
        String[] res = path.split("/");
        Stack st = new Stack();
        for(String s:res){
            if(s.equals(".")==true||s.equals("")==true){
                ;
            }
            else if(s.equals("..") == true){
                if(st.empty() == false)
                    st.pop();
            }
            else{
                st.push(s);
            }
        }
        String tes = "";
        while(st.empty() == false){
            tes = "/" + st.pop() + tes;
        }
        if(tes.length() == 0)
            tes = "/";
        return tes;
}