提供hack数据亦可。

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int t, n;
ll a[4];
void solve() {
	ll cnt = 0;
	a[1] = a[2] = a[3] = 0;
	scanf("%d", &n);
	for(int i = 1, x;i <= n;++i) {
		scanf("%d", &x);
		a[3] += 1ll*x/3, ++a[x%3];
	}
	if(a[3] <= a[1]) {
		cnt += a[3];
		a[1] -= a[3];
		printf("%lld\n", cnt+a[1]+a[2]);
		return;
	}
	cnt += a[1];
	a[3] -= a[1];
	if(a[3] <= 2*a[2]) {
		cnt += a[3];
		a[2] -= a[3]/2;
		printf("%lld\n", cnt+a[2]);
		return;
	}
	a[3] -= 2*a[2];
	cnt += a[2]*2;
	printf("%lld\n", cnt+(a[3]*3+3)/4);
}
int main () {
	scanf("%d", &t);
	while(t--) solve();
	return 0;
}