LeetCode_71_Simplify Path (Java)

71. Simplify Path

Medium

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You are given an absolute path for a Unix-style file system, which always begins with a slash '/'. Your task is to transform this absolute path into its simplified canonical path.

The rules of a Unix-style file system are as follows:

• A single period '.' represents the current directory.
• A double period '..' represents the previous/parent directory.
• Multiple consecutive slashes such as '//' and '///' are treated as a single slash '/'.
• Any sequence of periods that does not match the rules above should be treated as a valid directory or file name. For example, '...' and '....' are valid directory or file names.

The simplified canonical path should follow these rules:

• The path must start with a single slash '/'.
• Directories within the path must be separated by exactly one slash '/'.
• The path must not end with a slash '/', unless it is the root directory.
• The path must not have any single or double periods ('.' and '..') used to denote current or parent directories.

Return the simplified canonical path.

 

Example 1:

Example 2:

Example 3:

Example 4:

Example 5:

 

Constraints:

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

문제 풀이

/로 split 한 뒤 ..에 대한 경우의수를 나누었고 아무것도 없는 조건에서 바로 리턴하는 조건문도 추가했다.

코드

class Solution {
    public String simplifyPath(String path) {
        String[] dirArr = path.split("/");
        Deque<String> dq = new ArrayDeque<>();

        for(int i=0; i<dirArr.length; i++){
            if(!dirArr[i].equals(".") && !dirArr[i].isEmpty()){
                if(dirArr[i].equals("..")){
                    if(!dq.isEmpty()) dq.pollLast();
                }
                else{
                    dq.addLast(dirArr[i]);
                }
            }
        }
        StringBuilder sb = new StringBuilder();

        // case4 위한 조건문
        if(dq.isEmpty()) return "/";

        while(!dq.isEmpty()){
            sb.append("/").append(dq.poll());
        }
        return sb.toString();
    }
}