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  1. #include <stdio.h>
  2. #include<math.h>
  3. #include<stdlib.h>
  4. long long fact(long long a)
  5. {   long long r=1;
  6.     while(a>1)
  7.     {   r*=a;
  8.         a-=1;
  9.     }
  10.     return r;
  11. }
  12.  
  13. int main(void) {
  14. 	long long t;
  15. 	long long an;
  16. 	long double ans;
  17. 	scanf("%lld",&t);
  18. 	while(t--)
  19. 	{   long long N,K,n,k,d,fn,fk,fd;
  20. 	    scanf("%lld%lld",&N,&K);
  21. 	    n=N/2;
  22. 	    k=K/2;
  23. 	    d=n-k;
  24. 		if((d==0)||(k==0))
  25. 			exit(0);
  26. 	    fn=fact(n);
  27. 	    fk=fact(k);
  28. 	    fd=fact(d);
  29. 	    ans=((fn*(fk+1))/(fd*fk));
  30. 	    an=fmod(ans,1000000007);
  31. 	    printf("%lld\n",an);
  32. 	}   
  33. 	return 0;
  34. }
  35.  
Success #stdin #stdout 0s 2164KB
comments (?)
stdin 
2
13 9
10 6
stdout 
375
70
https://ideone.com/mFJLsw
language:
C (clang 8.0)
created:
10 years ago
visibility:
public

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