C++ 代码

#include <iostream>
#include <string>
using namespace std;

string s="";

string f(int &i){
    string ans="";
    while(i < s.length()){
        if(s[i] == '#'){
            i++;
            return ans;
        }
        else if(s[i]>='0' && s[i]<='9'){
            int sum=0;
            while(s[i]>='0' && s[i]<='9'){
                sum = sum*10+(s[i++]-'0');
            }
            i++;
            string ss = f(i);
            for(int j=0;j < sum;j++)
                ans+= ss;
        }
        while((s[i]<'0' || s[i]>'9') && s[i] !='#' && i<s.length())
            ans += s[i++];
    }
    return ans;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>s;
    int i=0;
    cout<<f(i)<<endl;
    return 0;
}