Difficulty: Medium
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. For more information, see:
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"
Language: Java
class Solution {
public String simplifyPath(String path) {
String[] split = path.split("/");
Deque<String> strings = new LinkedList<>(); // 使用双端队列
for (String s : split) {
if (!s.equals("") && !s.equals(".")) {
if (s.equals("..")) {
if (!strings.isEmpty()) {
strings.pop(); // 双端队列可以用作栈，返回上一层目录
}
} else {
strings.push(s); // 双端队列压栈写入头部元素
}
}
}
if (strings.isEmpty()) {
return "/";
}
StringBuilder stringBuilder = new StringBuilder();
while (!strings.isEmpty()) {
stringBuilder.append("/");
stringBuilder.append(strings.pollLast()); // 出尾部元素
}
return stringBuilder.toString();
}
}