71. Simplify Path

[ ] 71. Simplify Path

Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.

In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level.

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

Example 1:
```
Input: "/home/"
Output: "/home"
Explanation: Note that there is no trailing slash after the last directory name.
```
Example 2:
```
Input: "/../"
Output: "/"
Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
```
Example 3:
```
Input: "/home//foo/"
Output: "/home/foo"
Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.
```
Example 4:
```
Input: "/a/./b/../../c/"
Output: "/c"
```
Example 5:
```
Input: "/a/../../b/../c//.//"
Output: "/c"
```
Example 6:
```
Input: "/a//b////c/d//././/.."
Output: "/a/b/c"
```

题解

直接用栈解的，效果还不错

class Solution {
    public String simplifyPath(String path) {
        StringBuilder sb = new StringBuilder();

        String[] split = path.split("/");

        Stack stack = new Stack();
        for (int i = 0 ; i < split.length; i++) {
            if (split[i].isEmpty() || split[i].equals(".")) {
                continue;
            }

            if (split[i].equals("..")) {
                if (stack.isEmpty()) continue;
                stack.pop();
            } else {
                stack.push(split[i]);
            }

        }

        if (stack.isEmpty()) return "/";

        Object[] objects = stack.toArray();
        for (int i = 0; i < objects.length; i++) {
            sb.append("/");
            sb.append(objects[i]);
        }

        return sb.toString();
    }
}