[编程题-蘑菇街]回文串

#include<iostream>
#include<string>
using namespace std;
bool f(string& s, int i)
{
    int l = 0, r = s.size() - 1;
    if (l == i) l++;
    if (r == i) r--;
    while (l<r)
    {
        if (s[l] != s[r])
            return false;
        l++;
        r--;
        if (l == i) l++;
        if (r == i) r--;
    }
    return true;

}
int main()
{
    //string s="jnwbbwnjb";
    string s;
    while (cin >> s)
    {
        int n = s.size();
        if (n == 0 || n == 1) cout << "YES" << endl;
        else
        {
            bool flag = false;
            for (int i = -1; i<n; i++)
            {
                if (f(s, i))
                {
                    flag = true;
                    break;
                }
            }
            cout << (flag ? "YES" : "NO") << endl;
        }
    }
    return 0;
}