看不出来哪里算错了，请指教：

#include <iostream>
#include <algorithm>
using namespace std;

#define N 5001
int arr[N][2];

int main() {
	int n;
	int term = 0;
	double ave = 0, sum = 0;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> arr[i][0];
		arr[i][1] = i;
	}
	//用二维数组的第一个数存这个数，第二个数存一开始的序号
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n - i; j++) {
			if (arr[j][0] > arr[j + 1][0]) {
				swap(arr[j][0], arr[j + 1][0]);
				swap(arr[j][1], arr[j + 1][1]);
			}

		}
	}
	
	for (int i = 1; i <= n; i++) {
		term += arr[i][0];
		sum += term;
	}
	for (int i = 1; i <= n; i++) {
		cout << arr[i][1] << " ";
	}
	cout << endl;
	ave = sum / n;
	printf("%.2lf", ave);
}