[NK] Niuke monthly race 48 D

The question

Given a $n$ Of length $a[]$, You can Arbitrary arrangement $a[]$

Finally make Alternating multiplication Maximum ( What is this? Look at the question )

Ideas

greedy

apparent ( Of course not. , I only say hi after the game

obviously We let And the largest number first add , Then calculate later Multiplication When , Contribution is the greatest

So we consider ( Big * Big )* Big + Small

$400$ Many people are greedy , Feel this greedy It's strange

code

$cosecant$ The bosses

const int N = 1e5+10 ,mod =  1e9+7;

int a[N],n,b[N];

void solve(){
    
	cin>>n;
	for(int i=1;i<=n;i++) cin>>b[i];
	sort(b+1,b+1+n);
	
	int j = 1;
	// even numbers   Used to add  ( Put the small one in the back and add )
	for(int i=n/2*2;i>=2;i-=2)  a[i] = b[j++];
	// Odd number   Used to ride  ( Put the big one in front of you )
	for(int i=1;i<=n;i+=2) a[i] = b[j++];
	
	int s = a[1];
	for(int i=2;i<=n;i++){
    
		if(i&1){
    // When it's odd   It's multiplication 
			s = 1ll*s*a[i]%mod;
		}else{
    // Even numbers are added 
			s = (s+a[i])%mod;
		}
	}
	cout<<s<<endl;
		
}