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();
    }
}