299. Bulls and Cows

class Solution {
public:
string getHint(string secret, string guess) {
int n=secret.size();
if(n==0)
return "0A0B";
int acount=0;
for(int i=0;i<n;i++)
{
if(secret[i]==guess[i])
acount++;
}
map<char,int> m;
for(int i=0;i<n;i++)
{
m[secret[i]]++;
}
int bcount=0;
for(int i=0;i<guess.size();i++)
{
if(m.find(guess[i])!=m.end())
{
if(m[guess[i]]>0)
{
bcount++;
m[guess[i]]--;
}
}
}
bcount-=acount;
return to_string(acount)+"A"+to_string(bcount)+"B";
}
};