题解 | 牛牛学数列4
牛牛学数列4
https://www.nowcoder.com/practice/586b114f52034688879342ba45779081
#include <iostream>
using namespace std;
int main() {
int n;
int i;
int sum=0;
cin>>n;
for(i=n;i>0;i--)
{
sum+=(n-i+1)*i;//20=(1+1+1+1)+(2+2+2)+(3+3)+(4)=4*1+3*2+2*3+1*4;
}
cout<<sum<<endl;
return 0;
}
#新手小白刷题#