题目是个递推写法

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

string a,b;
int res;
void turn(int i){
    if(a[i]=='*')   a[i]='o';
    else if(a[i]=='o')   a[i]='*';
    return ;
}
int main(){
    cin>>a>>b;

    for(int i=0;i+1<a.size();i++){
        if(a[i]!=b[i]){
            res++;
            turn(i);
            turn(i+1);
        }
    }
    cout<<res<<endl;
    return 0;
}