A了

#include<iostream>
using namespace std;
int main()
{
	int n, i, a, b, t,m;
	cin >> n;
	i = a = b = t = 1;
	m = 0;
	while(i <= n){
		if(i <= a){
			m += b;
		}
		else if(i > a){
			t++;
			a += t;
			b++;
			m += b;
		}
		i++;
	}
	cout << m;
	return 0;
}

AC哥来了 #include<iostream> using namespace std; int main() { int n, i, a, b, t,m; cin >> n; i = a = b = t = 1; m = 0; while(i <= n){ if(i <= a){ m += b; } else if(i > a){ t++; a += t; b++; m += b; } i++; } cout << m; return 0; }

#include<iostream>
using namespace std;
int main()
{
    int k,n=1;
    long long num=0;
    cin >> k;
    while(k>0)
    {
        if(k>=n)
        {
            num+=n*n;
            k-=n;
            n++;
        }
        else
        {
            num+=k*n;
            k=0;
        }
    }
    cout << num;
    return 0;
}
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#include<iostream>
int main()
{
    int k;
    int sum=0,v=1;
    std::cin>>k;
    for(int i=1;k>=v;i+=1)
    {
        k-=v;
        sum+=v*v;
        v+=1;
    }
    sum+=k*v;
    std::cout<<sum;
}

#include <iostream>
int main(){
    int n=1,sum=0,day; std::cin>>day;
    while(day>=n){
        sum+=n*n;
        day-=n; n++;}
    std::cout<<sum+day*n; return 0;}