System Longest File Path

问题

Suppose we abstract our file system by a string in the following manner:

The string "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext" represents:

The directory dir contains an empty sub-directory subdir1 and a sub-directory subdir2 containing a file file.ext.

The string

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

The directory dir contains two sub-directories subdir1 and subdir2. subdir1 contains a file file1.ext and an empty second-level sub-directory subsubdir1. subdir2 contains a second-level sub-directory subsubdir2 containing a file file2.ext.

We are interested in finding the longest (number of characters) absolute path to a file within our file system. For example, in the second example above, the longest absolute path is "dir/subdir2/subsubdir2/file2.ext", and its length is 32 (not including the double quotes).

Given a string representing the file system in the above format, return the length of the longest absolute path to file in the abstracted file system. If there is no file in the system, return 0.

注意事项

The name of a file contains at least a . and an extension.
The name of a directory or sub-directory will not contain a ..
Time complexity required: O(n) where n is the size of the input string.
Notice that a/aa/aaa/file1.txt is not the longest file path, if there is another path aaaaaaaaaaaaaaaaaaaaa/sth.png.
您在真实的面试中是否遇到过这个题？ Yes
样例
Give input = "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext" return

分析

大家按照要求做就可以了，这个好像不是太难。

代码

public class Solution {
    /*
     * @param input: an abstract file system
     * @return: return the length of the longest absolute path to file
     */
    public int lengthLongestPath(String input) {
        // write your code here
        String[] split = input.split("\n");
        List list = new ArrayList<>();
        int res = 0;
        for (String path : split) {
            String s = path.replace("\t", "");
            int depth = path.length() - s.length();
            list.add(depth, s);
            if (s.contains(".")) {
                String filePath = "";
                for (int i = 0; i <= depth; i++) {
                    filePath += list.get(i) + "/";
                }
                res = Math.max(filePath.length() - 1, res);
            }
        }
        return res;
    }
}