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  1. #include <bits/stdc++.h>
  2. #include <chrono>
  3. using namespace std;
  4. using namespace chrono;
  5. // "AJEET JAIN"----"JAI JINENDRA"
  6. /* "णमो अरिहंताणं",
  7.   "णमो सिद्धाणं",
  8.   "णमो आयरियाणं",
  9.   "णमो उवज्झायाणं",
  10.   "णमो लोए सव्वसाहूणं",
  11.   "",
  12.   "एसो पंच नमोक्कारो, सव्व पावप्पणासणो",
  13.   "मंगलाणं च सव्वेसिं, पडमं हवै मंगलं", */
  14.  
  15.  
  16. // Aliases to op
  17. using ll = long long;
  18. using ull = unsigned long long;
  19. using ld = double;
  20. using vll = vector<ll>;
  21.  
  22.  
  23. // Constants
  24. constexpr ll INF = 4e18;
  25. constexpr ld EPS = 1e-9;
  26. constexpr ll MOD = 1e9 + 7;
  27.  
  28.  
  29.  
  30. // Macros
  31. #define F first
  32. #define S second
  33. #define all(x) begin(x), end(x)
  34. #define allr(x) rbegin(x), rend(x)
  35. #define py cout<<"YES\n";
  36. #define pn cout<<"NO\n";
  37. #define forn(i,n) for(int i=0;i<n;i++)
  38. #define for1(i,n) for(int i=1;i<=n;i++)
  39.  
  40. // #define insert push_back
  41. #define pb push_back
  42. #define MP make_pair
  43. #define endl '\n'
  44.  
  45. /*
  46.   remove substring or subarray ---> try to think about sliding w
  47.  
  48.   */
  49.  
  50. /*
  51.  
  52.   Golden Rule
  53.  
  54.   1) problem is easy
  55.   2) proofs is easy
  56.   3) implementation is easy
  57.  
  58.   /*k = 4
  59.   ROUGH - 1 1 2 2 3 4 5 1
  60.  
  61.   */
  62.  
  63. void AJNJ(){
  64. ll n , k;
  65. cin >> n >> k;
  66. vector<int> b(n + 1);
  67. map<int , int> mp;
  68. for1(i , n){
  69. cin >> b[i];
  70. mp[b[i]]++;
  71. }
  72. ll cnt = 0;
  73.  
  74. for1(i , n){
  75. if(mp[k - b[i]] > 0){
  76. if(b[i] == k - b[i]){
  77. cnt += mp[k - b[i]] - 1;
  78. mp[b[i]]--;
  79. }
  80. else{
  81. cnt = cnt + mp[k - b[i]];
  82. mp[b[i]]--;
  83. }
  84. }
  85. }
  86.  
  87. cout << cnt << endl;
  88.  
  89. }
  90.  
  91.  
  92. int main(){
  93. ios::sync_with_stdio(0);
  94. cin.tie(0);
  95. cout.tie(0);
  96. int T = 1;
  97. cin>>T;
  98. auto start1 = high_resolution_clock::now();
  99. while(T--){
  100. AJNJ();
  101. }
  102. auto stop1 = high_resolution_clock::now();
  103. auto duration = duration_cast<microseconds>(stop1 - start1);
  104. cerr << "Time: " << duration . count() / 1000 << " ms" << endl;
  105.  
  106. return 0;
  107. }
  108.  
Success #stdin #stdout #stderr 0.01s 5288KB
stdin
Standard input is empty
stdout
0
stderr
Time: 0 ms