大佬提供一下思路吧

#include<iostream>
#include<algorithm>
using namespace std;
long long n,sum;
long long a[100005];
bool cmp(int x,int y){
	if(x>y){
		return x>y;
	}
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
    	cin>>a[i];
	}
	sort(a+1,a+n+1,cmp);
	for(int i=1;i<=n;i++){
		if(n<=2&&a[i]<a[i+1]){
			sum+=a[i+1];
			break;
		}
		else if(a[i]>a[i+1]&&n<=2){
			sum+=a[i];
			break;
		}
		else if(n!=2&&a[i]<a[i+1]){
			if(a[i+1]==true){
				break;
			}
			sum+=a[i+1];
			a[i+1]==true; 
		}
		else if(n!=2&&a[i]>a[i+1]){
			if(a[i]==true){
				break;
			}
			sum+=a[i];
			a[i]==true;
		}
	}
	cout<<sum;
    return 0;
}