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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. // 8
  28. // 1 2 1 3 2 0 1 0
  29.  
  30.  
  31.  
  32. vector<int> a;
  33.  
  34. int consistency(int n){
  35.  
  36. 	vector<int> pSmaller(n);
  37. 	for(int j=1; j<=n-1; j++){
  38. 		for(int i=j-1; i>=0; i--){
  39. 			if(a[i] < a[j]) pSmaller[j]++;
  40. 		}
  41. 	}
  42.  
  43. 	vector<int> sSmaller(n);
  44. 	for(int j=n-2; j>=0; j--){
  45. 		for(int i=j+1; i<n; i++){
  46. 			if(a[i] < a[j]) sSmaller[j]++;
  47. 		}
  48. 	}
  49.  
  50. 	int ans = 0;
  51.  
  52. 	for(int j=2; j<=n-3; j++){
  53.  
  54. 		int left = 0;
  55. 		for(int i=j-1; i>=1; i--){
  56. 			if(a[i] > a[j]) left += pSmaller[i];	
  57. 		}
  58.  
  59. 		int right = 0;
  60. 		for(int k=j+1; k<=n-2; k++){
  61. 			if(a[k] > a[j]) right += sSmaller[k];
  62. 		}
  63.  
  64. 		ans += left*right;
  65. 	}
  66.  
  67. 	return ans;
  68. }
  69.  
  70.  
  71.  
  72.  
  73.  
  74.  
  75.  
  76.  
  77.  
  78.  
  79.  
  80.  
  81.  
  82.  
  83.  
  84. int practice(int n){
  85.  
  86.  
  87.     return 0;
  88. }
  89.  
  90.  
  91.  
  92.  
  93.  
  94. void solve() {
  95.  
  96.     int n;
  97.     cin>> n;
  98.  
  99.     a.resize(n);
  100.     for(int i=0; i<n; i++) cin >> a[i];
  101.  
  102.     cout << consistency(n) << endl;
  103.  
  104.  
  105. }
  106.  
  107.  
  108.  
  109.  
  110.  
  111. int32_t main() {
  112.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  113.  
  114.     int t = 1;
  115.     // cin >> t;
  116.     while (t--) {
  117.         solve();
  118.     }
  119.  
  120.     return 0;
  121. }
Success #stdin #stdout 0.01s 5316KB
comments (?)
stdin
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8
1 2 1 3 2 0 1 0
stdout
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13
https://ideone.com/8YP7jQ
language:
C++14 (gcc 8.3)
created:
10 hours ago
visibility:
public

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