71.md

71. Simplify Path

In this problem, we need to process the UNIX

1. Note that the returned canonical path must always begin with a slash /,
2. and there must be only a single slash / between two directory names.
3. The last directory name (if it exists) must not end with a trailing /.
4. Also, the canonical path must be the shortest string representing the absolute path.

For requirement 1,2 we need to add / or Delete redundant slash

But there is also a .. question.

Oh, I try to use stack to solve this problem. we split it by using slash. If we face a .. we need to pop. if we face a string not "." or "" we push it in our stack. Finally we output the stack in the reverse order.