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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	//code
  6. 	int t;
  7. 	cin>>t;
  8. 	while(t--)
  9. 	{
  10. 	    //formula based :
  11. 	    //if last second digit is odd : 4*Fact of(no/5)* Fact of(no%10)
  12. 	    //if last second digit is even : 6*Fact of(no/5)* Fact of(no%10)
  13. 	    int n,check,lastd;
  14. 	    cin>>n;
  15. 	    int a[10]; // stores factorials last digit from 0 to 9
  16. 	    a[0]=1;
  17. 	    for(int i=1;i<10;i++)
  18. 	    {
  19. 	        a[i]=i*a[i-1];
  20. 	        while(a[i]%10==0)
  21. 	        {
  22. 	            a[i]=a[i]/10;
  23. 	        }
  24. 	        a[i]=a[i]%10;
  25. 	    }
  26.  
  27.  
  28. 	    check=(n%100)/10;
  29. 	    //cout<<check<<endl;
  30. 	    if(check%2!=0)
  31. 	    {
  32. 	       lastd= 4*a[n/5]*a[n%10];
  33. 	       lastd=lastd%10;
  34. 	    }
  35. 	    else
  36. 	    {
  37. 	    lastd=6*a[n/5]*a[n%10];
  38. 	    lastd=lastd%10;
  39. 	    }
  40. 	    cout<<lastd<<'\n';
  41. 	}
  42. 	return 0;
  43. }
Success #stdin #stdout 0s 4316KB
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stdout
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https://ideone.com/1QjrzA
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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