[bzoj 3751][noip 2014] 解方程

#include <list>
const int MAXN = 105;
const int MAXM = 1000005;
const int MAXLEN = 10005;
const int PRIME_NUM = 2;
const int MODS[PRIME_NUM] = {21893, 18341629};
int n, m;
int a[MAXN];
char s[MAXN][MAXLEN];
int (char *s, int mod) {
    int sgn = 1, res = 0;
    if (*s == '-') sgn = -1, s++;
    for (; *s; s++) res = (res * 10 + *s - '0') % mod;
    return res * sgn;
}
int calc(int x, int mod) {
    long long res = 0, pow = 1;
    for (int i = 0; i <= n; i++) {
        res = (res + a[i] * pow) % mod;
        pow = pow * x % mod;
    }
    return (int) res;
}
int main() {
    scanf("%d %d", &n, &m);
    for (int i = 0; i <= n; i++) scanf("%s", s[i]);
    std::list<int> roots;
    int p = MODS[0];
    for (int i = 0; i <= n; i++) a[i] = parseInt(s[i], p);
    for (int i = 1; i < p; i++) {
        int y = calc(i, p);
        if (y == 0) for (int j = i; j <= m; j += p) roots.push_back(j);
    }
    for (int i = 1; i < PRIME_NUM; i++) {
        int p = MODS[i];
        for (int j = 0; j <= n; j++) a[j] = parseInt(s[j], p);
        for (std::list<int>::iterator it = roots.begin(); it != roots.end(); ) {
            int y = calc(*it, p);
            if (y != 0) it = roots.erase(it);
            else it++;
        }
    }
    roots.sort();
    printf("%lun", roots.size());
    for (std::list<int>::iterator it = roots.begin(); it != roots.end(); it++) 
        printf("%dn", *it);
    return 0;
}