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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.  
  27.  
  28.  
  29. int consistency1(int n, int k) {
  30.  
  31. 	int ans = 0;
  32. 	int s = 0, e = n-1;
  33.  
  34. 	//* keep in mind  s<e   (Not s<=e )
  35. 	while(s<e){
  36. 		if(a[s] + a[e] > k){
  37. 			e--;
  38. 		}
  39. 		else{
  40. 			ans += (e-s);
  41. 			s++;
  42. 		}
  43. 	}
  44. 	return ans;
  45.  
  46. }
  47.  
  48.  
  49. //* Template 2 : 
  50. //* 	Invalid window => sum > k   
  51. //* 	Valid window   =>  sum <= k
  52.  
  53. int consistency2(int n, int k) {
  54.  
  55.  
  56. 	int ans = 0;
  57. 	int s = 0, e = n-1;
  58.  
  59. 	while(s<e){
  60.  
  61. 		while(s<e && a[s]+a[e] > k) e--;
  62. 		if(s==e) break;
  63.  
  64. 		ans += (e-s);
  65. 		s++;
  66. 	}
  67. 	return ans;
  68.  
  69. }
  70.  
  71.  
  72.  
  73.  
  74.  
  75.  
  76.  
  77.  
  78.  
  79. int practice(int n, int k) {
  80.  
  81. 	int ans = 0;
  82. 	int s = 0, e = n-1;
  83. 	while(s<e){
  84.  
  85. 		while(e>s && a[s] + a[e] > k) e--;
  86. 		if(e==s) break;
  87.  
  88. 		ans += e-s;
  89. 		s++;
  90. 	}
  91.  
  92.  
  93. 	return ans;
  94. }
  95.  
  96.  
  97. void solve() {
  98.  
  99. 	int n, k;
  100. 	cin >> n >> k;
  101.  
  102. 	a.resize(n);
  103.  
  104. 	for(int i=0; i<n; i++) cin >> a[i];
  105.  
  106.     // cout << consistency1(n, k) << " " <<  consistency2(n, k) << endl;
  107.  
  108.     cout << consistency1(n, k) << " -> " << practice(n, k) << endl;
  109.  
  110. }
  111.  
  112.  
  113.  
  114.  
  115.  
  116. int32_t main() {
  117.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  118.  
  119.     int t = 1;
  120.     // cin >> t;
  121.     while (t--) {
  122.         solve();
  123.     }
  124.  
  125.     return 0;
  126. }
Success #stdin #stdout 0.01s 5308KB
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https://ideone.com/C73oT1
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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