1165E - Two Arrays and Sum of Functions - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define SHAHD-BATGURL
#define pi 3.14159265359
#define des sort(arr, arr+n, greater <>());
#define asc sort(arr, arr+n);
#define mxarr *max_element(arr, arr+n);
#define mnarr *min_element(arr, arr+n);
#define remove_duplicates s.erase(unique(s.begin(), s.end()), s.end());
#define erase_char s.erase(remove(s.begin(), s.end(), '+'), s.end());
#define count_char count(s.begin(), s.end(), 'U');
#define speed ios_base::sync_with_stdio(0); cin.tie(0);
ll const mod=1e9+7;
//ll dx[4]={0, 0, 1, -1, 1, 1, -1, -1};
//ll dy[4]={0, 0, 1, -1, -1, 1, -1, 1};
int dx[4]= {0, 0, 1, -1};
int dy[4]= {1, -1, 0, 0};
//ll const mod=1e9+7;
ll arr[200005];
ll arr1[200005];
#define speed ios_base::sync_with_stdio(0); cin.tie(0);
int main()
{
    speed;
    ll n, sum=0;
    cin>>n;
    for(int i=0; i<n; i++)
    {
        cin>>arr[i];
        arr[i]*=((i+1)*(n-i));
    }
    for(int i=0; i<n; i++)
        cin>>arr1[i];
    sort(arr, arr+n);
    sort(arr1, arr1+n, greater<>());
    for(int i=0; i<n; i++)
    {
        sum+=((arr[i]%998244353)*(arr1[i]%998244353))%998244353;
        sum%=998244353;
    }
    cout<<sum;
    return 0;
}