nyoj 122 Triangular Sums

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

这是道阅读题 英语不好是硬伤

思路 ：T(N)=1+2+3+.....+N ; SUM=1*T(2)+2*T(3)+3*T(4)+......N*T(N+1)（注意：b[1]=a[2]）

#include<stdio.h>
int main()
{
    int a[305],b[305],t,c=1;;
    scanf("%d",&t);
    a[0]=1;
    for(int i=1;i<=305;i++)
        a[i]=i*(i+1)/2;
    b[1]=a[2];
    for(int i=2;i<=300;i++)
        b[i]=b[i-1]+a[i+1]*i;
    while(t--)
    {

        int n;
        scanf("%d",&n);
        printf("%d %d %d\n",c++,n,b[n]);
    }
    return 0;
}