1753C - Wish I Knew How to Sort - CodeForces Solution

// Problem: C. Wish I Knew How to Sort
// Contest: Codeforces - Codeforces Round #829 (Div. 1)
// URL: https://codeforces.com/contest/1753/problem/C
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<utility>
#include<set>
#include<unordered_set>
#include<list>
#include<iterator>
#include<deque>
#include<queue>
#include<stack>
#include<set>
#include<bitset>
#include<random>
#include<map>
#include<unordered_map>
#include<stdio.h>
#include<complex>
#include<math.h>
#include<cstring>
#include<chrono>
#include<string>

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("no-stack-protector")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,popcnt,abm,mmx,tune=native")
// #pragma GCC optimize("fast-math") 

using namespace std;
#define int long long int
#define pb push_back
#define ff first
#define ss second
#define vi vector <int>
#define vvi vector <vi>
#define pii pair<int, int>
#define ppi pair<pii, int>
#define vii vector<pii>
#define mii map<int, int>
#define mci map<char, int>
#define miv map<int, vi>
#define mis map<int, set<int>>
#define setbits(n) __builtin_popcount(n)
#define all(v) (v).begin(), (v).end()
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define endl "\n"
#define fo(i,n) for(int i=0;i<n;i++)
#define in(a,n)	for(int i=0;i<n;i++) cin>>a[i];
#define show2(a, b) cout<<a<<' '<<b<<endl
#define show3(a, b, c) cout<<a<<' '<<b<<' '<<c<<endl
#define show(arr) for (auto i:arr) cout<<i<<' '; 
#define Endl endl
const long long N=1e5+5;
const long long mod=998244353;
int inv(int i) {if (i == 1) return 1; return (mod - ((mod / i) * inv(mod % i)) % mod) % mod;} 

int gcd(int a, int b) { if (b == 0) return a; return gcd(b, a % b);}
 
int ceil_div(int a, int b) {return a % b == 0 ? a / b : a / b + 1;}
 
int pwr(int a, int b) {a %= mod; int res = 1; while (b > 0) {if (b & 1) res = res * a % mod; a = a * a % mod; b >>= 1;} return res;}
int n;
vi a;
void cases(){
	cin>>n;
	a.clear();a.resize(n);in(a,n);
	int cnt=0;for(int i=0;i<n;i++)cnt+=a[i];
	int z=n-cnt;
	int k=0;
	for(int i=0;i<z;i++)k+=a[i];
	int ans=0,num=(n*(n-1)/2)%mod;
	// cout<<k<<endl;
	for(int i=1;i<=k;i++)
	{
		(ans+=(num*inv((i*i)%mod))%mod)%=mod;
	}
	cout<<ans<<endl;
}

int32_t main(){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    int t=1;
    cin>>t;
    for (int i=0; i<t; i++){
    	//cout<<"Case #"<<i+1<<": ";
		cases();
    }
    return 0;
}