Practice/Meta/Unix Cd Command with Symbolic Link Resolution

Unix Cd Command with Symbolic Link Resolution

CodingMust

Problem

You are building a file system navigation utility that simulates changing directories similar to the Unix cd command. Your implementation must handle absolute paths, relative paths with special directory references (. for current and .. for parent), and symbolic links that redirect to other paths in the file system.

Given a current working directory path, a target path to navigate to, and a mapping of symbolic links, determine the final absolute path after resolving all navigation operations and symlink redirections. If a circular symlink reference is detected, return the string "CYCLE_DETECTED".

Requirements

1. Process absolute paths (starting with /) by replacing the current path entirely
2. Process relative paths by starting from the current directory
3. Handle . (current directory) and .. (parent directory) references correctly
4. Resolve symbolic links when encountered during path traversal
5. Detect cycles in symbolic link chains and return "CYCLE_DETECTED"
6. Normalize the final path by removing redundant slashes and directory references
7. Handle edge cases such as navigating above root directory (stay at /)

Constraints

• Current path is always a valid absolute path
• Target path length: 0 ≤ length ≤ 1000
• Number of symbolic links: 0 ≤ n ≤ 100
• Symbolic link paths are always absolute
• Path components contain only alphanumeric characters, dots, underscores, and hyphens
• Time complexity target: O(n) where n is the total length of paths processed
• Space complexity target: O(d) where d is the maximum directory depth

Examples

Example 1:

Input: current_path = "/home/user" target_path = "docs/projects" symlinks = \{\} Output: "/home/user/docs/projects" Explanation: Relative path appended to current directory with no symlinks

Example 2:

Input: current_path = "/a/b/c" target_path = "../../d" symlinks = \{\} Output: "/a/d" Explanation: Navigate up two levels from /a/b/c to /a, then down into d

Example 3:

Input: current_path = "/usr" target_path = "local/bin" symlinks = \{"/usr/local": "/opt/custom"\} Output: "/opt/custom/bin" Explanation: Path /usr/local is a symlink to /opt/custom, so final path becomes /opt/custom/bin

Example 4:

Input: current_path = "/home" target_path = "link/file" symlinks = \{"/home/link": "/tmp/other", "/tmp/other": "/home/link"\} Output: "CYCLE_DETECTED" Explanation: Circular reference detected between /home/link and /tmp/other