---
tags: leetcode
---

# [388. Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path/)
---
# My Solution
## The Key Idea for Solving This Coding Question
## C++ Code

struct pathData {
    int pathLen;
    int level;
    pathData(int pathLen, int level) : pathLen(pathLen), level(level) {}
};

class Solution {
public:
    int lengthLongestPath(string input) {
        int i = 0;
        int longestLen = 0;
        stack<pathData> st;

        while (i < input.size()) {
            if (input[i] == '\n') {
                ++i;
            }

            int level = 0;
            while (i < input.size() && input[i] == '\t') {
                ++level;
                ++i;
            }

            int nameLen = 0;
            bool isFile = false;
            while (i < input.size() && input[i] != '\n') {
                if (input[i] == '.') {
                    isFile = true;
                }
                ++nameLen;
                ++i;
            }
            if (!isFile) {
                ++nameLen; // append the '/' for directory.
            }


            while (!st.empty() && st.top().level >= level) {
                st.pop();
            }

            if (st.empty()) {
                st.push(pathData(nameLen, level));
            } else {
                st.push(pathData(st.top().pathLen + nameLen, level));
            }

            if (isFile && longestLen < st.top().pathLen) {
                longestLen = st.top().pathLen;
            }
            
        }

        return longestLen;
    }
};

## Time complexity
$O(n)$
$n$ is the length of `path`.
## Space complexity
$O(L)$
$L$ is the level of the filesystem hierarchy.
# Miscellane
<!--
# Test Cases

"dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext"

"dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext"

"a"

"file1.txt\nfile2.txt\nlongfile.txt"

-->