How hard is LeetCode 388. Longest Absolute File Path?

LeetCode 388. Longest Absolute File Path is rated Medium on LeetCode.

What is the time complexity of LeetCode 388. Longest Absolute File Path?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 388. Longest Absolute File Path?

The Python solution on this page uses O(n) auxiliary space.

What topics does LeetCode 388. Longest Absolute File Path cover?

LeetCode 388. Longest Absolute File Path is tagged Stack, Depth-First Search and String on LeetCode.

Longest Absolute File Path — LeetCode 388 Python Solution

MediumStackDepth-First SearchString

Problem: #388
Pattern: Stack
Reading time: 6 min
Source: leetcode.com

The problem

Suppose we have a file system that stores both files and directories. An example of one system is represented in the following picture: Here, we have dir as the only directory in the root.

Example

dir
⟶ subdir1
⟶ ⟶ file1.ext
⟶ ⟶ subsubdir1
⟶ subdir2
⟶ ⟶ subsubdir2
⟶ ⟶ ⟶ file2.ext

Python solution

Python

class Solution:
    def lengthLongestPath(self, input: str) -> int:
        i, n = 0, len(input)
        ans = 0
        stk = []
        while i < n:
            ident = 0
            while input[i] == '\t':
                ident += 1
                i += 1

            cur, isFile = 0, False
            while i < n and input[i] != '\n':
                cur += 1
                if input[i] == '.':
                    isFile = True
                i += 1
            i += 1

            # popd
            while len(stk) > 0 and len(stk) > ident:
                stk.pop()

            if len(stk) > 0:
                cur += stk[-1] + 1

            # pushd
            if not isFile:
                stk.append(cur)
                continue

            ans = max(ans, cur)

        return ans

Complexity

Measure	Complexity
Time	O(n)
Space	O(n) auxiliary

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 388. Longest Absolute File Path is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Stack.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 388. Longest Absolute File Path?: LeetCode 388. Longest Absolute File Path is rated Medium on LeetCode.
What is the time complexity of LeetCode 388. Longest Absolute File Path?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 388. Longest Absolute File Path?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 388. Longest Absolute File Path cover?: LeetCode 388. Longest Absolute File Path is tagged Stack, Depth-First Search and String on LeetCode.