我的力扣主页：
https://leetcode-cn.com/u/cutesnake/

4.20
388中等
https://leetcode-cn.com/problems/longest-absolute-file-path/
乍一看简单，仔细一想不会做。本来想用遍历，看了答案知道用哈希表，但还是太难办，写了一个小时，wa一次，有点理解屎山是如何堆成的了……

class Solution {
public:
    int lengthLongestPath(string input) {
        int res = 0, curLen = 0, subCnt = 0, n = input.size();
        bool isFile = 0;
        unordered_map<int, int> subNum;
        for (int i = 0; i < n; ++i) {
            char& ch = input[i];
            if (ch == '\n') {
                isFile = 0;
                subNum[subCnt] = curLen;
                subCnt = 0;
                continue;
            }
            if (ch == '\t') {
                ++subCnt;
            } else {
                if (i && (input[i-1] == '\t' || (input[i-1] == '\n' && subCnt == 0))) curLen = subNum[subCnt-1];
                if (ch == '.') isFile = 1;
                ++curLen;
                if (isFile) res = max(res, curLen + subCnt);
            }
        }
        return res;
    }
};