Help me in solving TWOCLOSE problem

My issue

explain the approach and issue in my code

My code

#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here
	int t;
	cin>>t;
	while(t--){
	    int n;
	    int arr[n+1];
	    for(int i=0;i<n+1;i++){
	        cin>>arr[i];
	    }
	    int minsum=0,sum=0;
	    for(int i=0;i<n;i++){
	        minsum=minsum+arr[i];
	    }
	    for(int i=0;i<n+1;i++){
	        if(arr[i]<=2*arr[n]){
	            int temp=arr[i];
	            arr[i]=arr[n];
	            arr[n]=temp;
	        }
	        for(int i=0;i<n;i++){
	            sum=sum+arr[i];
	            
	        }
	         if(minsum<sum)
	            minsum=sum;
	       
	   }
	    cout<<minsum<<endl;
	}

}

Problem Link: Not-too-far Replacement Practice Coding Problem