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poj--3086
escription
The nth 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)]
Input
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.
Output
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.
Sample Input
4 3 4 5 10
Sample Output
1 3 45 2 4 105 3 5 210 4 10 2145
具体代码:
#include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> using namespace std; int main() { int t, n; scanf("%d", &t); for (int i = 0; i < t; i++) { scanf("%d", &n); int w = 0, x = 1; for (int j = 1; j <= n; j++) { x += j + 1; w += j * x; } printf("%d %d %d\n", i + 1, n, w); } return 0; }