class Solution {

public:

string decodeString(string s) {

stack<string> mystack;

for(auto e:s)

{

if(e != ']')

mystack.push(string() += e);

//如果是]，则开始匹配左[找到[]中的内容

else

{

string str;

while(mystack.top() != "[")

{

str += mystack.top();

mystack.pop();

}

//让栈顶的[出栈

mystack.pop();

//获取栈顶数字，将字符串str重复

string num;

while((!mystack.empty()) && (mystack.top()[0] >= '0' && mystack.top()[0] <= '9'))

{

num += mystack.top()[0];

mystack.pop();

}

string::iterator itB = num.begin();

string::iterator itE = num.end();

reverse(itB,itE);

for(int i = 1;i <= stoi(num);i++)

mystack.push(str);

}

}

//从栈中将字符串取出，得到结果

string result;

while(!mystack.empty())

{

result += mystack.top();

mystack.pop();

}

string::iterator itB = result.begin();

string::iterator itE = result.end();

reverse(itB,itE);

return result;

}

};