判断一个字符串是否为回文

#include <iostream>

using namespace std;
bool judge(string );

int main()
{
string str;
cin >> str;
if(judge(str))
cout<<"YES"<<endl;
else cout<<"NO";
return 0;
}
bool judge(string str){

bool flag = true;
for(int i=0;i<str.length();i++ )
{
if(str[i] != str[str.length()-i-1])
flag = false;
}
return flag;

}