編程之美 大神與三個小夥伴

#include <iostream>
#include <cmath>

using namespace std;

const long long great = 1000000007;

bool isSame(long long a, long long b, long long c)
{
	if (a == b && b == c)
		return true;
	if (a == b)
		return false;
	if (b == c)
		return false;
	if (c == a)
		return false;

	return true;
}

int main()
{
	int T;
	cin >> T;

	for (int i = 0; i < T; ++i) {
		long long N;
		cin >> N;
		long long sum = 0;
		for (long long A = 1; A <= N; ++A)
			for (long long B = 1; B <= N; ++B)
				for (long long C = 1; C <= N; ++C) {
					if (!isSame(A, B, C))
						continue;
					long long temp = 0;
					temp = (N - A + 1) * (N - B + 1) * (N - C + 1);
					sum = (sum + temp) % great;
				}
		cout << "Case " << i + 1 << ": " << sum << endl;;
	}

	return 0;
}

注意了 C++中的 unsigned long long int 是64Bit 也就是18位,