在下面的程序中,我们根据给定的n
和r
值计算 nPr 的值。 nPr 也可以表示为P(n, r)
。P(n, r)
的公式是n! /(n - r)!
,例如 P(6, 2)= 6! /(6-2)! => 720/24 = 30
。我们在下面的 C 程序中实现了相同的逻辑。
#include <stdio.h>
void main()
{
int n, r, npr_var;
printf("Enter the value of n:");
scanf("%d", &n);
printf("\nEnter the value of r:");
scanf("%d", &r);
/* nPr is also known as P(n,r), the formula is:
* P(n,r) = n! / (n - r)! For 0 <= r <= n.
*/
npr_var = fact(n) / fact(n - r);
printf("\nThe value of P(%d,%d) is: %d",n,r,npr_var);
}
// Function for calculating factorial
int fact(int num)
{
int k = 1, i;
// factorial of 0 is 1
if (num == 0)
{
return(k);
}
else
{
for (i = 1; i <= num; i++)
{
k = k * i;
}
}
return(k);
}
输出:
Enter the value of n:
5
Enter the value of r:
2
The value of P(6,2) is: 30