Medium

Quiz

#388 Longest Absolute File Path

APPROACH

A file system is serialized into a single string input. Each line represents one entry; leading tab characters ('\t') encode nesting depth — one tab per level. Entries whose name contains a dot are files; all others are directories.

The absolute path to an entry is formed by joining its ancestor directory names and its own name with '/'.

Return the number of characters in the longest absolute path that terminates at a file. Return 0 when no file is present in the input. Every entry name is guaranteed non-empty.

Example 1:

dir

⟶ subdir1

⟶ ⟶ file1.ext

⟶ ⟶ subsubdir1

⟶ subdir2

⟶ ⟶ subsubdir2

⟶ ⟶ ⟶ file2.ext

Example 2:

Input: input = "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext"

Output: 20

Explanation: We have only one file, and the absolute path is "dir/subdir2/file.ext" of length 20.

Example 3:

Input: input = "dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext"

Output: 32

Explanation: We have two files:

"dir/subdir1/file1.ext" of length 21

"dir/subdir2/subsubdir2/file2.ext" of length 32.

We return 32 since it is the longest absolute path to a file.

Example 4:

Input: input = "a"

Output: 0

Explanation: We do not have any files, just a single directory named "a".

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What is the optimal approach for this problem?