计划C / C ++中的模块化方程的解数的程序吗?
在这里,我们将看到一个与模块化方程有关的有趣问题。假设我们有两个值A和B。我们必须找到变量X可以采用的可能值的数量,使得(AmodX)=B成立。
假设A是26,而B是2。因此X的首选值将是{3,4,6,8,8,12,24}因此,计数将是6。这就是答案。让我们看看该算法以获得更好的主意。
算法
PossibleWayCount(a,b)-
begin if a = b, then there are infinite solutions if a < b, then there are no solutions otherwise div_count := find_div(a, b) return div_count end
find_div(a,b)-
begin n := a – b div_count := 0 for i in range 1 to square root of n, do if n mode i is 0, then if i > b, then increase div_count by 1 end if if n / i is not same as i and (n / i) > b, then increase div_count by 1 end if end if done end
示例
#include <iostream> #include <cmath> using namespace std; int findDivisors(int A, int B) { int N = (A - B); int div_count = 0; for (int i = 1; i <= sqrt(N); i++) { if ((N % i) == 0) { if (i > B) div_count++; if ((N / i) != i && (N / i) > B) //ignore if it is already counted div_count++; } } return div_count; } int possibleWayCount(int A, int B) { if (A == B) //if they are same, there are infinity solutions return -1; if (A < B) //if A < B, then there are two possible solutions return 0; int div_count = 0; div_count = findDivisors(A, B); return div_count; } void possibleWay(int A, int B) { int sol = possibleWayCount(A, B); if (sol == -1) cout << "For A: " << A << " and B: " << B << ", X can take infinite values greater than " << A; else cout << "For A: " << A << " and B: " << B << ", X can take " << sol << " values"; } int main() { int A = 26, B = 2; possibleWay(A, B); }
输出结果
For A: 26 and B: 2, X can take 6 values