[LeetCode] 71. Simplify Path - 문제풀이

Description

절대 경로가 주어졌을때 이를 단순화된 표준경로로 변환하여 반환하는 문제입니다.

=Given a string path, which is an absolute path (starting with a slash '/') to a file or directory in a Unix-style file system, convert it to the simplified canonical path.

In a Unix-style file system, a period '.' refers to the current directory, a double period '..' refers to the directory up a level, and any multiple consecutive slashes (i.e. '//') are treated as a single slash '/'. For this problem, any other format of periods such as '...' are treated as file/directory names.

The canonical path should have the following format:

• The path starts with a single slash '/'.
• Any two directories are separated by a single slash '/'.
• The path does not end with a trailing '/'.
• The path only contains the directories on the path from the root directory to the target file or directory (i.e., no period '.' or double period '..')

Return the simplified canonical path.

Example 1:

Input: path = "/home/"
Output: "/home"
Explanation: Note that there is no trailing slash after the last directory name.

Example 2:

Input: path = "/../"
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: path = "/home//foo/"
Output: "/home/foo"
Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.

Constraints:

• 1 <= path.length <= 3000
• path consists of English letters, digits, period '.', slash '/' or '_'.
• path is a valid absolute Unix path.

Solution 1. Stack

public static String simplifyPath(String path) {

    Stack<String> stack = new Stack();
    
    for(String str: path.split("/")){
        if(str.equals("..")) {
            if(!stack.empty()) stack.pop();
        }
        else if(str.length()>0 && !str.equals(".")) stack.push(str);
    }

    return "/"+String.join("/",stack);

}

스택을 사용하여 가장 안쪽 뎁스의 유효한 폴더부터 넣어주고 ..일경우 이전 디렉토리 경로를 하나 삭제한뒤 마지막에 join을 통해 stack의 모든 경로를 /로 붙여서 내보냅니다.

Reference

Simplify Path - LeetCode