Triangular Sums 南阳acm122

Triangular Sums

时间限制：3000 ms  |  内存限制：65535 KB

难度：2

 

描述

The n^th Triangular number, T(n) = 1 + … + n, is the sum of the first n integers. It is the number of points in a triangular array with n points on side. For example T(4):

X
X X
X X X
X X X X

Write a program to compute the weighted sum of triangular numbers:

W(n) = SUM[k = 1…n; k * T(k + 1)]

 

输入

The first line of input contains a single integer N, (1 ≤ N ≤ 1000) which is the number of datasets that follow.

Each dataset consists of a single line of input containing a single integer n, (1 ≤ n ≤300), which is the number of points on a side of the triangle.

输出

For each dataset, output on a single line the dataset number (1 through N), a blank, the value of n for the dataset, a blank, and the weighted sum ,W(n), of triangular numbers for n.

样例输入

4
3
4
5
10

样例输出

1 3 45
2 4 105
3 5 210
4 10 2145

来源

Greater New York 2006

上传者

张云聪

题目：比如这个三角形有4层，他的第一层为1.....第四层为4，T(n)=1+2+3+4;但是他不是让我们求T(n),让我们求W(n)，W(n)=k*T(k+1); (k=1,2,....n);

然后输出的这三位分别是：第一位 1-t(t是多少组测试数据)，第二位是 n(就是你输入的n)，第三位是 W(n)，(英语不好，别见怪哈~) 具体看代码实现：

 

#include<stdio.h>
//用来求T（n）,1+2+3+...n;
int f(int n)
{
  int i,ans;
  ans=0;
  for(i=1;i<=n;i++)
      ans+=i;
  return ans;
}
int main()
{
  int t,a;
  a=1;    //用来计1到t;
  scanf("%d",&t);
  while(t--)
  {
    int i,n,k,ans;
    ans=0;
    k=1;
    scanf("%d",&n);
    //用来求W(n)
    for(i=0;i<n;i++)
    {
      ans+=(k*f(k+1));
      k++;
    }
    printf("%d %d %d\n",a++,n,ans);
  }
  return 0;
}