P2010 [NOIP2016 普及组] 回文日期

#include 
using namespace std;
vector<int> date;
int d[] = {0,31,29,31,30,31,30,31,31,30,31,30,31};
int atoi(string s)
{
    return atoi(s.c_str());
}
int main()
{
    int cnt = 0;
    int a,b;
    cin >> a >> b;
    for(int i = 1;i <= 12;i++)
    {
        for(int j = 1;j <= d[i];j++)
        {
            int num1 = i * 100 + j;
            string s = to_string(num1);
            reverse(s.begin(),s.end());
            if(s.size() == 3)   s += "0";
            int num = atoi(s) * 10000 + num1;
            if(num >= a && num <= b)
            {
                cnt++;
            }
        }
    }
    cout << cnt << endl;
    return 0;
}