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  1. /*
  2. *DIV 2 C.
  3. *LINK:
  4. *nilabja10201992
  5. */
  6. #include <bits/stdc++.h>
  7. using namespace std;
  8.  
  9. #define inf (1<<30)
  10. #define INF (int)1e9
  11. #define EPS 1e-9
  12. #define PI 3.1415926535897932384626433832795
  13. #define MOD 1000000007
  14. #define MAX 1000000
  15.  
  16. int n,k;
  17. int arr[MAX];
  18. int bsearch(int a,int i){
  19. 	int l=i;
  20. 	int r=n-1;
  21. 	int cnt=0;
  22. 	while(l<=r){
  23. 		int m=(l+r)/2;
  24. 		if(abs(arr[m]-a)==k)
  25. 			cnt++;
  26. 		if(abs(arr[m]-a)>=k)
  27. 			r=m-1;
  28. 		else if(abs(arr[m]-a)<k)
  29. 			l=m+1;
  30. 	}
  31. 	l=0;
  32. 	r=i;
  33. 	while(l<=r){
  34. 		int m=(l+r)/2;
  35. 		if(abs(arr[m]-a)==k)
  36. 			cnt++;
  37. 		if(abs(arr[m]-a)>=k)
  38. 			l=m+1;
  39. 		else if(abs(arr[m]-a)<k)
  40. 			r=m-1;
  41. 	}
  42. 	return cnt;
  43. }
  44. int main() {
  45.       ios_base::sync_with_stdio(false);
  46.       cin.tie(NULL);
  47. 	cin>>n>>k;
  48. 	for(int i=0;i<n;i++)
  49. 		cin>>arr[i];
  50. 	sort(arr,arr+n);
  51. 	int ans=0;
  52. 	for(int i=0;i<n;i++){
  53. 		int a=arr[i];
  54. 		ans+=bsearch(arr[i],i);
  55. 	}
  56. 	cout<<ans/2<<endl;
  57. 	//cout<<"Execution time : "<<tick();
  58.       return 0;
  59. }
  60.  
Success #stdin #stdout 0s 19144KB
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https://ideone.com/omo7gy
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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