32-语言入门-32-Triangular Sums

题目地址： http://acm.nyist.net/JudgeOnline/problem.php?pid=122 

 

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

 

 

英文没咋看懂，重要的是这个公式：

W(n) = SUM[k = 1…n; k * T(k + 1)]

 

从1开始遍历到输入的n k

k* sum[1-(k+1)]

然后将各个项相加取和

 

最终输入的格式是：

序号 输入的数值 最终的和

 

代码：

 

#include <stdio.h>

static int getSum(int num);

int main()
{
     int readLen = 0;
     scanf("%d",&readLen);
     getchar();
    
     int index = 1;
     while(readLen > 0)
     {
          int num = 0;
          scanf("%d",&num);
          getchar();
         
          int sum = getSum(num);
          printf("%d %d %d\n",index,num,sum);
          ++index;
         
          --readLen;
     }
    
     return 0;
}

static int getSum(int num)
{
     int index = 1;
     int result = 0;
     int tmpSum = 1;
     for(;index <= num;++index)
     {
          tmpSum += (index+1);
          result += index*tmpSum;
     }
    
     return result;
}