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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. #define print(a)         for(auto x : a) cout << x << " "; cout << endl
  6.  
  7.  
  8. const int M = 1000000007;
  9. const int N = 3e5+9;
  10. const int INF = 2e9+1;
  11. const int LINF = 2000000000000000001;
  12.  
  13. inline int power(int a, int b, int mod=M) {
  14.     int x = 1;
  15.     a %= mod;
  16.     while (b) {
  17.         if (b & 1) x = (x * a) % mod; 
  18.         a = (a * a) % mod;
  19.         b >>= 1;
  20.     }
  21.     return x;
  22. }
  23.  
  24.  
  25. //_ ***************************** START Below *******************************
  26.  
  27.  
  28.  
  29.  
  30. vector<int> a;
  31.  
  32. int consistency1(int n){
  33.  
  34. 	int ans = 0;
  35.  
  36. 	for(int j=1; j<=n-2; j++){
  37.  
  38. 		int ct1 = 0;
  39. 		int i = j-1;
  40. 		while(i>=0){
  41. 			if(a[i] > a[j]) ct1++;
  42. 			i--;
  43. 		}
  44.  
  45. 		int ct2 = 0;
  46. 		int k = j+1;
  47. 		while(k<n){
  48. 			if(a[k] > a[j]) ct2++;
  49. 			k++;
  50. 		}
  51.  
  52. 		ans += (ct1 * ct2);
  53. 	}
  54.  
  55. 	return ans;
  56.  
  57. }
  58.  
  59.  
  60.  
  61. //* Followup : 
  62.  
  63. int consistency2(int n){
  64.  
  65. 	int ans = 0;
  66.  
  67. 	for(int j=1; j<=n-3; j++){
  68. 		for(int k=j+1; k<=n-2; k++){
  69.  
  70. 			if(a[j] >= a[k]) continue;
  71.  
  72. 			int ct1 = 0;
  73. 			int i = j-1;
  74. 			while(i>=0){
  75. 				if(a[i] > a[j]) ct1++;
  76. 				i--;
  77. 			}
  78.  
  79. 			int ct2 = 0;
  80. 			int l = k+1;
  81. 			while(l<=n-1){
  82. 				if(a[l] < a[k]) ct2++;
  83. 				l++;
  84. 			}
  85.  
  86. 			ans += ct1*ct2;
  87.  
  88. 		}
  89. 	}
  90.  
  91. 	return ans;
  92. }
  93.  
  94.  
  95.  
  96.  
  97. int consistency3(int n){
  98.  
  99. 	int ans = 0;
  100.  
  101. 	vector<int> pCountGreaterThan(n, 0);
  102. 	for(int j=1; j<=n-1; j++){
  103. 		int i = j-1;
  104. 		while(i>=0){
  105. 			if(a[i] > a[j]) pCountGreaterThan[j]++;
  106. 			i--;
  107. 		}
  108. 	}
  109.  
  110. 	vector<int> sCountSmallerThan(n, 0);
  111. 	for(int k=0; k<=n-2; k++){
  112. 		int l = k+1;
  113. 		while(l<=n-1){
  114. 			if(a[l] < a[k]) sCountSmallerThan[k]++;
  115. 			l++;
  116. 		}
  117. 	}
  118.  
  119. 	for(int j=1; j<=n-3; j++){
  120. 		for(int k=j+1; k<=n-2; k++){
  121.  
  122. 			if(a[j] >= a[k]) continue;
  123.  
  124. 			ans += pCountGreaterThan[j] * sCountSmallerThan[k];
  125.  
  126. 		}
  127. 	}
  128.  
  129. 	return ans;
  130. }
  131.  
  132.  
  133.  
  134.  
  135.  
  136.  
  137.  
  138.  
  139.  
  140.  
  141.  
  142.  
  143.  
  144.  
  145.  
  146.  
  147.  
  148.  
  149.  
  150.  
  151. int practice(int n){
  152.  
  153.  
  154.     return 0;
  155. }
  156.  
  157.  
  158.  
  159.  
  160.  
  161. void solve() {
  162.  
  163.     int n;
  164.     cin>> n;
  165.  
  166.     a.resize(n);
  167.     for(int i=0; i<n; i++) cin >> a[i];
  168.  
  169.     cout << consistency1(n) << endl;
  170.     cout << "Followup => " << consistency2(n) << " " << consistency3(n) << endl;
  171.  
  172.  
  173. }
  174.  
  175.  
  176.  
  177.  
  178.  
  179. int32_t main() {
  180.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  181.  
  182.     int t = 1;
  183.     // cin >> t;
  184.     while (t--) {
  185.         solve();
  186.     }
  187.  
  188.     return 0;
  189. }
Success #stdin #stdout 0s 5316KB
comments (?)
stdin
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7
8 3 6 1 7 2 5
stdout
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17
Followup => 13 13
https://ideone.com/WB35cF
language:
C++14 (gcc 8.3)
created:
6 days ago
visibility:
public

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