测试点全部RE，代码也没发现问题，有大佬能帮帮我忙QAQ

#include<bits/stdc++.h>
using namespace std;
int a[5001];
int main(){
    int minn,minnn,n,b=0,t,l;
    cin>>n;
    for (int i=1;i<=n;i++)
    cin>>a[i];
    for (int i=1;i<=n;i++){
        for (int j=1;j<=n;j++){
            if (a[j]!=-1&&a[j]<minn){
                minn=a[j];
                l=j;
            }
        }
        for (int j=1;j<=n;j++){
            if (l!=j&&a[j]!=-1&&a[j]<minnn){
                minnn=a[j];
                t=j;
            }
        }
        b+=minnn+minn;
        a[t]=b;
        a[l]=-1;
    }
    cout<<b;
    return 0;
}