snws [Round 1]. Special Dates

#include <cstdio>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <string>

using namespace std;

int  months[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30 ,31, 30, 31};
const int MAXL = 20;

int d, m, y;
string s;
char c[MAXL];
int k[MAXL];

int rec(string s, int n = 0)
{
    if (n == 3)
    {
//        cout << s << endl;
        int n = s.size() - 1;
        bool f = true;
        for (int i = 1; i + i <= n; i++)
            if (s[i] != s[n - i + 1])
            {
                f = false;
                break;
            }
        if (f) return true;

        int x;
        x = k[1] = 0;
        for (int i = 2; i <= n; i++)
        {
            while (x && s[x + 1] != s[i]) x = k[x];
            x += s[x + 1] == s[i];
            k[i] = x;
        }
        if (x && n % (n - x) == 0) return true;

        return false;
    }

    int x;
    switch (n)
    {
        case 0:
        case 1:
            x = n == 0? d : m;
            sprintf(c, "%02d", x);
            if (rec(s + c, n + 1)) return true;
            if (x < 10)
            {
                sprintf(c, "%d", x);
                if (rec(s + c, n + 1)) return true;
            }
        break;

        case 2:
            sprintf(c, "%d", y);
            if (rec(s + c, n + 1)) return true;
            sprintf(c, "%d", y % 100);
            if (rec(s + c, n + 1)) return true;
        break;
    }

    return false;
}

int main()
{
    freopen("special.in", "r", stdin);
    freopen("special.out", "w", stdout);
    scanf("%d %d %d", &d, &m, &y);
    months[2] = 28 + (int)(y % 400 == 0 || y % 4 == 0 && y % 100 != 0);

    do
    {
        if (rec(" "))
            break;

        d++;
        if (months[m] < d)
        {
            d = 1;
            m++;
            if (12 < m)
            {
                y++;
                m = 1;
                months[2] = 28 + (int)(y % 400 == 0 || y % 4 == 0 && y % 100 != 0);
            }
        }
    } while (true);
    printf("%d %d %d\n", d, m, y);
    return 0;
}