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  1. #include <stdio.h>
  2.  
  3. int factorial(int n)
  4. {
  5. 	int i,rtn=1;
  6. 	if(n > 0)
  7. 	{
  8. 		for(i=1;i<n+1;i++)
  9. 		{
  10. 			rtn *= i;
  11. 		}
  12. 		return rtn;
  13. 	}
  14. 	else if(n == 0)
  15. 	{
  16. 		return rtn;
  17. 	}
  18. 	else
  19. 	{
  20. 		printf("error");
  21. 		return 0;
  22. 	}
  23. }
  24.  
  25. int comb(int m, int k)
  26. {
  27. 	int rtn;
  28. 	rtn = factorial(m) / (factorial(k) * factorial(m-k));
  29. 	return rtn;
  30. }
  31. int main(void) 
  32. {
  33. 	int m,k,ans;
  34. 	scanf("%d %d",&m,&k);
  35. 	ans = comb(m,k);
  36. 	printf("%d個の中から%d個を取り出す組合せ数は、%d通りです。",m,k,ans);
  37. }
  38.  
Success #stdin #stdout 0s 5316KB
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10個の中から3個を取り出す組合せ数は、120通りです。
https://ideone.com/wiA1XD
language:
C (gcc 8.3)
created:
2 days ago
visibility:
public

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