609. Find Duplicate File in System

Find Duplicate File in System

Problem Description

Given a list paths of directory info, including the directory path, and all the files with contents in this directory, return all the duplicate files in the file system in terms of their paths. You may return the answer in any order.

A group of duplicate files consists of at least two files that have the same content.

A single directory info string in the input list has the following format:

• "root/d1/d2/.../dm f1.txt(f1_content) f2.txt(f2_content) ... fn.txt(fn_content)"

It means there are n files (f1.txt, f2.txt ... fn.txt) with content (f1_content, f2_content ... fn_content) respectively in the directory "root/d1/d2/.../dm". Note that n >= 1 and m >= 0. If m = 0, it means the directory is just the root directory.

The output is a list of groups of duplicate file paths. For each group, it contains all the file paths of the files that have the same content. A file path is a string that has the following format:

• "directory_path/file_name.txt"

 

Example 1:

Input: paths = ["root/a 1.txt(abcd) 2.txt(efgh)","root/c 3.txt(abcd)","root/c/d 4.txt(efgh)","root 4.txt(efgh)"]
Output: [["root/a/2.txt","root/c/d/4.txt","root/4.txt"],["root/a/1.txt","root/c/3.txt"]]

Example 2:

Input: paths = ["root/a 1.txt(abcd) 2.txt(efgh)","root/c 3.txt(abcd)","root/c/d 4.txt(efgh)"]
Output: [["root/a/2.txt","root/c/d/4.txt"],["root/a/1.txt","root/c/3.txt"]]

 

Constraints:

• 1 <= paths.length <= 2 * 104
• 1 <= paths[i].length <= 3000
• 1 <= sum(paths[i].length) <= 5 * 105
• paths[i] consist of English letters, digits, '/', '.', '(', ')', and ' '.
• You may assume no files or directories share the same name in the same directory.
• You may assume each given directory info represents a unique directory. A single blank space separates the directory path and file info.

 

Follow up:

• Imagine you are given a real file system, how will you search files? DFS or BFS?
• If the file content is very large (GB level), how will you modify your solution?
• If you can only read the file by 1kb each time, how will you modify your solution?
• What is the time complexity of your modified solution? What is the most time-consuming part and memory-consuming part of it? How to optimize?
• How to make sure the duplicated files you find are not false positives?

 

Note:

No order is required for the final output.

You may assume the directory name, file name, and file content only has letters and digits, and the length of the file content is in the range of [1,50].

The number of files given is in the range of [1,20000].

You may assume no files or directories share the same name in the same directory.

You may assume each given directory info represents a unique directory. Directory path and file info are separated by a single blank space.

Follow-up beyond contest:

• Imagine you are given a real file system, how will you search files? DFS or BFS?
• If the file content is very large (GB level), how will you modify your solution?
• If you can only read the file by 1kb each time, how will you modify your solution?
• What is the time complexity of your modified solution? What are the most time-consuming part and memory-consuming parts of it? How to optimize?
• How to make sure the duplicated files you find are not false positives?

let`s Code it:

/**
 * @param {string[]} paths
 * @return {string[][]}
 */
var findDuplicate = function(paths) {
    const hashmap = {};

    for (let path of paths) {
        const [folder, ...files] = path.split(" ");
        for (let file of files) {
          const lpi = file.indexOf("(");
          const rpi = file.lastIndexOf(")");
          const filename = file.slice(0, lpi);
          const content = file.slice(lpi, rpi);
          const fullname = `${folder}/${filename}`;
          if (!hashmap[content]) hashmap[content] = [];
          hashmap[content].push(fullname);
        }
    }

    return Object.values(hashmap).filter(q => q.length >= 2);
};

Time Complexity: O(N + C) where N is the total number of files and C is the number of different keys in Map
Space Complexity: O(N) for N files in Map

Conclusion

That’s all folks! In this post, we solved LeetCode problem #609. Find Duplicate File in System

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You can find the complete source code on my GitHub repository. If you like what you learn. feel free to fork 🔪 and star ⭐ it.

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Happy coding!