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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int count1=0;
  5. void rec(string S,int b,int i)
  6. {
  7. 	//cout<<"S="<<S<<endl;
  8.  
  9. 	string S2 = to_string(b);
  10. 	if(i == S2.length())
  11. 	{
  12. 		if(S != "" && stoi(S) <= b)
  13. 		{
  14. 			count1++;
  15. 		}
  16. 		return;
  17. 	}
  18. 	else
  19. 	{
  20. 		if(i == 0)
  21. 		{
  22. 			for(int j=0;j<10;j++)
  23. 			{
  24. 				if(j ==0 && S=="")
  25. 				{
  26. 					rec(S,b,i+1);
  27. 				}
  28. 				else
  29. 				{
  30. 					string s = S;
  31. 					s+=(j+'0');
  32. 					rec(s,b,i+1);
  33. 				}
  34. 			}
  35. 		}
  36. 		else
  37. 		{
  38. 			for(int j=0;j<10;j++)
  39. 			{
  40. 				if(S.back() != (j+'0'))
  41. 				{
  42. 					if(j ==0 && S=="")
  43. 					{
  44. 						rec(S,b,i+1);
  45. 					}
  46. 					else
  47. 					{
  48. 						string s = S;
  49. 						s+=(j+'0');
  50. 						rec(s,b,i+1);
  51. 					}
  52. 				}
  53. 			}
  54. 		}
  55. 	}
  56. }
  57.  
  58. int main() {
  59.  
  60. 	long long a,b;
  61. 	cin>>a>>b;
  62.  
  63. 	count1=0;
  64. 	rec("",b,0);
  65. 	int countb=count1;	
  66.  
  67. 	count1=0;
  68. 	rec("",a-1,0);
  69. 	int counta=count1;
  70.  
  71. 	cout<<countb-counta<<endl;
  72.  
  73. 	return 0;
  74. }
Success #stdin #stdout 0.01s 5280KB
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https://ideone.com/McxUfV
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language:
C++14 (gcc 8.3)
created:
10 days ago
visibility:
public

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