题解 | #牛牛的排列数#
牛牛的排列数
https://www.nowcoder.com/practice/9ca1c236cdbf46da9e08e1f510808625
#include <stdio.h>
int A_(int n, int m) {
if (n < m)
return 0;
else {
long long a1 = 1;
long long a2 = 1;
int i = 0;
for (i = n; i > 0; a1 *= i, i--);
for (i = n - m; i > 0; a2 *= i, i--);
return (a1 / a2);
}
}
int main() {
int n, m;
scanf("%d %d", &n, &m);
printf("%d", A_(n, m));
return 0;
}
