题解 | 练一下前缀和
牛牛学数列4
https://www.nowcoder.com/practice/586b114f52034688879342ba45779081
#include<iostream>
using namespace std;
int main()
{
int n;cin>>n;
int a[n+1],b[n+1];
a[0]=0;b[0]=0;
for(int i=1;i<=n;i++)a[i]=a[i-1]+i;
for(int i=1;i<=n;i++)b[i]=b[i-1]+a[i];
cout<<b[n];
return 0;
}//前缀和练手
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