内存超限 $80\%$ ，求改正：

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
long long q,cnt_1,cnt_2;
string s,w;
int main()
{
    cin>>q;
    cin>>s;
    cin>>w;
    for (long long i=0;i<q;i++)
    {
        if (w[i]=='1')
            cnt_1++;
        else
            cnt_2++;
    }
    long long len=s.size()-1;
    if (cnt_1%2==1)
    {
        string tmp="";
        for (long long i=len;i>=0;i--)
            tmp=tmp+s[i];
        for (long long i=0;i<=len;i++)
            s[i]=tmp[i];
    }
    if (cnt_2%2==1)
    {
        for (long long i=0;i<=len;i++)
        {
            if (s[i]=='1')
                s[i]='0';
            else
                s[i]='1';
        }
    }
    cout<<s;
}