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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int long long int
  4. #define double long double
  5. inline int power(int a, int b) {
  6. int x = 1;
  7. while (b) {
  8. if (b & 1) x *= a;
  9. a *= a;
  10. b >>= 1;
  11. }
  12. return x;
  13. }
  14.  
  15.  
  16. const int M = 1000000007;
  17. const int N = 3e5+9;
  18. const int INF = 2e9+1;
  19. const int LINF = 2000000000000000001;
  20.  
  21. //_ ***************************** START Below *******************************
  22.  
  23.  
  24.  
  25. vector<int> a;
  26. void consistency(int n, int k) {
  27.  
  28. unordered_map<int,int> mp;
  29. int ans = 0;
  30. for(int i=0; i<n; i++){
  31. if(mp.count(a[i] - k)){
  32. ans += mp[a[i]-k];
  33. }
  34. if(k!=0 && mp.count(a[i] + k)){
  35. ans += mp[a[i]+k];
  36. }
  37. mp[a[i]]++;
  38. }
  39. cout << ans << endl;
  40. }
  41.  
  42. void solve() {
  43.  
  44. int n, k;
  45. cin >> n >> k;
  46. a.resize(n);
  47. for(int i=0; i<n; i++) cin >> a[i];
  48. consistency(n, k) ;
  49.  
  50. }
  51.  
  52.  
  53.  
  54.  
  55.  
  56. int32_t main() {
  57. ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  58.  
  59. int t = 1;
  60. while (t--) {
  61. solve();
  62. }
  63.  
  64. return 0;
  65. }
Success #stdin #stdout 0.01s 5276KB
stdin
5 2
1 5 3 4 2
stdout
3