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”.
這個題目重點就是要了解它的意思，如果是一個點 . 那就是目前路徑，不管，如果是兩個點 .. 那就是目前路徑的上一個目錄。這樣我們用棧來表示的話，就是如下所示
明白這個之後就一目了然了，就是注意傳回的時候如果是”/”或者”/../”這種情形就行。
另一種連結清單的做法