那个第二题 2[a1[b]]有没有做的呢？ 我的是：为嘛通过率0  ^_^(勿喷，菜鸡) #include<iostream> #include<string> #include<algorithm> #include<sstream> using namespace std; int main() {     string str;     cin >> str;     int len = str.length();     int startpos;     int endpos;          string res;     int cnt;     for (int i = len - 1; i >= 1; i--)     {         if (str[i] == '[' )         {             string tmp;             startpos = i;             for (int j = i+1; j <len-1; j++)             {                 if (str[j]  >='a' && str[j] <= 'z' || str[j] >= 'A' && str[j] <= 'Z')                     tmp += str[j];                 else                     break;             }             string cntk;             bool isexit = false;             for (int k = i; k >= 0; k--)             {                 if (str[k] >= '0' && str[k] <= '9')                 {                     isexit = true;                     cntk = str[k] + cntk;                 }                 else                     if (isexit == true)                         break;                              }             stringstream ss;             ss << cntk;             ss >> cnt;                      tmp =  tmp +res;             string s;             res = s;                      for (int k = 0; k < cnt; k++)             {                 res += tmp;             }         }     }     cout << res << endl;     system("pause"); }