What is wrong with my code?
please help!
#include <bits/stdc++.h>
using namespace std;
void solve(string str){
int n = str.length();
string str1;
int carry=0;
for(int i=n-1;i>=0;i--){
int a=(str[i]-'0')*2+carry;
str1+=(char)(a%10+'0');
carry=a/10;
//cout<<carry<<" "<<a<<endl;
}
if(carry>0)
str1+=(char)(carry+'0');
//cout<<str1<<endl;
carry=2;
for(int i=0;i<str1.size();i++){
int a=str1[i] - '0';
if(a>1){
str1[i]=(str1[i]- '0' - carry + 10)%10 + '0';
break;
// cout<<str1[i]<<endl;
}
else{
str1[i]=(str1[i]- '0' - carry + 10)%10 + '0';
carry=1;
}
}
reverse(str1.begin(),str1.end());
bool fl=0;
for(int i=0;i<str1.size();i++){
if(str1[i]=='0' && fl==0)
continue;
cout<<str1[i];
fl=1;
}
cout<<endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
string str;
while(cin>>str){
if(str=="1" || str=="0")
cout<<str<<endl;
else
solve(str);
}
//cout<<"Execution time : "<<tick();
return 0;
}
