原来超时了，时间复杂度O(n²)，现在O(n)，不超时但WA

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

long long n, a[200010], cnt, sum;
int main()
{
	cin >> n;
	for(int i = 1; i <= n; i++) cin >> a[i];
	for(int i = 1; i <= n; i++)
	{
		a[i] += sum;
		if(a[i] == 0) continue;
		cnt += abs(a[i]);
		if(a[i] < 0)
		{
			sum += (i + 1) * abs(a[i]);
			a[i] = 0;
		}
		else
		{
			sum -= abs(a[i]) * (i + 1);
			a[i] = 0;
		}
		cout << sum << endl;
	}
	cout << cnt << endl;
	return 0;
}

给个思路呗。