394. Decode String

394. Decode String
这题花了不少时间，明明是考察栈的知识，用stack或者手写递归就行，我就是半天写不出，想起来之前有一道写什么miniparse的题还是最长文件路径的题，还有这类解析什么的题，反正自己写的代码比较丑，贴出来吧。

class Solution {
public:
    string work(string s, int &x, int n) {
        if(x > n) return "";
        int t = 0;
        string s1 = "";
        int tag1 = x;
        while(x < n && !isdigit(s[x])) x++;
        s1 = s.substr(tag1, x - tag1);
        if(x == n) return s1;
        while(x < n && isdigit(s[x])) {
            t = t * 10 + s[x] - '0'; x++;
        }
        if(s[x] == '[') {
            x++;
            int id = x;
            while(x < n && !isdigit(s[x]) && s[x] != ']') x++;
            if(s[x] == ']') {
                string t1 = "", t2 = s.substr(id, x - id);
                for (int i = 0; i < t; i++) t1 += t2;
                x++;
                if(x == n) return s1 + t1;
                if(x < n) {
                        //cout << "t1 " << x << endl;
                    if(s[x] == ']') return s1 + t1;
                    else return s1 + t1 + work(s, x, n);
                }

            } else {
                //cout << "td " <<x <<endl;
                string t0 = s.substr(id, x - id);
                //cout << "asd " << x << endl;
                string t1 = "", t2 = work(s, x, n);

                //cout << t0 << " test " << t2 << " " << x << endl;
                t2 = t0 + t2;
                for (int i = 0; i < t; i++) t1 += t2;
                x++;
                //cout << x<< " " <<t1 <<  endl;
                if(x == n) return s1 + t1;
                else {
                    if(s[x] == ']') return s1 + t1;

                    return s1 + t1 + work(s, x, n);
                }

            }
        }
        return "";
    }

       string decodeString(string s) {
           int x = 0;
            return work(s, x, s.size());
    }
};