1452B - Toy Blocks - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define int long long
#define rep(i, a, n) for(int i = a; i <= n; i++)
#define per(i, a, n) for(int i = n; i >= a; i--)
typedef pair<int, int> PII;
const int N = 1e5 + 10;
int a[N];
void solve(){
	//try it again.
	int n; cin >> n;
	rep(i, 1, n) cin >> a[i];
	int ma = 0, sum = 0;
	rep(i, 1, n) ma = max(ma, a[i]), sum += a[i];
	int cnt = ma * (n - 1);
	if(cnt < sum){
		int c = sum / (n - 1);
		if(sum % (n - 1)) c++;
		cnt = c * (n - 1);
	}
	cout << cnt - sum << '\n';
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int t = 1;
	cin >> t;
	while(t--)
	solve();
}