【題解】Codeforces 1305C. Kuroni and Impossible Calculation

#include <iostream>
#include <vector>
using namespace std;
 
int n, mod, a;
long long ans;
vector <int> v;
 
int main() {
    cin >> n >> mod;
    if (n > mod) cout << 0 << "\n";
    else {
        ans = 1;
        for (int i = 0; i < n; i++){
            cin >> a;
            v.push_back(a);
            for (int j = 0; j < i; j++){
                ans *= abs(v[j]-v[i]);
                ans %= mod;
            }
        }
        cout << ans << "\n";
    }
}