394.leetcode Decode String(medium)[栈 字符串]

iven an encoded string, return it's decoded string.

The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is guaranteed to be a positive integer.

You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc.

Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, k. For example, there won't be input like 3a or 2[4].

Examples:

s = "3[a]2[bc]", return "aaabcbc".
s = "3[a2[c]]", return "accaccacc".
s = "2[abc]3[cd]ef", return "abcabccdcdcdef".

class Solution {
public:
   string decodeString(string s) {
        //思路其实有点像计算器的思想，用栈存放[]符号，当遇到第一次匹配的括号时得到base string
        stack letter;
        stack num;//记录次数
        int n = s.length();
        string result;
        for(int i = 0;i=0;i--)
                         {
                             letter.push(last[i]);
                         }
                    }else
                    {
                        reverse(last.begin(),last.end());
                        result += last;
                        if(letter.top() == '[')
						   letter.pop(); 
                    }
                }
            }
        }
        if(!letter.empty()&&num.empty())
        {
             string temp="";
             while(!letter.empty())
             {
                 temp += letter.top();
                 letter.pop();
             }
             reverse(temp.begin(),temp.end());
             result += temp;
        }
        return result;
    }
};