1305C - Kuroni and Impossible Calculation - CodeForces Solution

#include <bits/stdc++.h>
#define ll long long 
using namespace std;
int main(){
    ll n,m;
    cin>>n>>m;
    ll arr[n];
    set<ll>s;
    for(ll i=0;i<n;i++){
        cin>>arr[i];
        s.insert(arr[i]);
    }
    ll ans=1;
    if(n>1000 || s.size()!=n){
        cout<<0<<endl;
    }
    else {
        bool flag=true;
        for(ll i=0;i<n;i++){
            for(ll j=i+1;j<n;j++){
                ans=(ans*(abs(arr[j]-arr[i]))%m)%m;
               // cout<<ans<<endl;
                if(ans==0){
                    flag=false;
                    break;
                    
                }
            }
            if(flag==false)break;
        }
        cout<<ans<<endl;
    }
}