This requires programming problem, according to the formula C n m = m ! ( N - m ) ! N ! Is calculated from the extraction of n different elements of m elements ( m ≤ n) of the number of combinations.
It is recommended to define and call function fact(n)calculations n!, where nthe type is intand the function type is double.
Input format:
The input gives two positive integers m and n ( m ≤ n) on one line, separated by spaces.
Output format:
Output according to the format "result = calculation result of number of combinations". The title guarantees that the result is within the doublecategory.
Sample input:
2 7
Sample output:
result = 21
#include<stdio.h>
int main ()
{
double fact(int n);
int m,n;
double sum=0;
scanf("%d%d",&m,&n);
if(m<=n)
{
sum=1.0*fact(n)/(fact(m)*fact(n-m));
printf("result = %.0lf",sum);
}else
{
scanf("%d%d",&m,&n);
}
return 0;
}
double fact(int n)
{
int i;
double sum=1;
for(i=1;i<=n;i++)
{
sum*=i;
}
return sum;
}