Simplify Path

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

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

click to show corner cases.

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".

这一题思路很清晰，使用stack来做。只是最后输出的时候要以队列的方式输出。

/../ 返回上一层

/./ 当前层

public class Solution {
    public String simplifyPath(String path) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(path == null) return null;
        String[] element = path.split("/");
        Stack<String> st = new Stack<String>();
        for(int i = 0; i < element.length; i ++){
            if(element[i].length() != 0){
                if(element[i].equals("..")){
                    if(st.isEmpty() != true)
                        st.pop();
                }else if(element[i].equals(".")){
                }else{
                    st.push(element[i]);
                }
            }
        }
        StringBuffer sb = new StringBuffer();
        if(st.isEmpty() == true){
            sb.append("/");
        }else{
            for(int i = 0; i < st.size(); i ++){
                sb.append("/");
                sb.append(st.elementAt(i));
            }   
        }
        return sb.toString();
    }
}

 第三遍：

public class Solution {
    public String simplifyPath(String path) {
        String[] parts = path.split("/");
        LinkedList<String> ll = new LinkedList<String> ();
        for(int i = 0; i < parts.length; i ++){
            System.out.println(parts[i]);
            if(parts[i].equals("") || parts[i].equals(".") || (parts[i].equals("..") && ll.size() == 0)) continue;
            else if(parts[i].equals("..") && ll.size() != 0) ll.removeLast();
            else ll.add(parts[i]);
        }
        StringBuffer sb = new StringBuffer();
        while(ll.size() != 0){
            sb.append("/");
            sb.append(ll.remove());
        }
        if(sb.length() == 0) sb.append("/");
        return sb.toString();
    }
}