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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 consistency(int n){
  33.  
  34. 	int total = 0;
  35. 	vector<int> prefix(n+1, 0);
  36.  
  37. 	for(int i=0; i<n; i++){
  38. 		prefix[i+1] = prefix[i] + a[i];
  39. 		total += a[i];
  40. 	}
  41.  
  42. 	if(total % 3 != 0) return false;
  43.  
  44. 	int ans = 0;
  45. 	for(int i=1; i<=n-2; i++){
  46. 		for(int j=i+1; j<=n-1; j++){
  47. 			int leftSum = prefix[i];
  48. 			int midSum = prefix[j] - prefix[i];
  49. 			if(leftSum == total/3 && midSum == total/3 ) ans++;
  50. 		}
  51. 	}
  52.  
  53. 	return ans;
  54.  
  55. }
  56.  
  57.  
  58.  
  59.  
  60.  
  61.  
  62.  
  63.  
  64.  
  65.  
  66.  
  67.  
  68.  
  69.  
  70.  
  71. int practice(int n){
  72.  
  73.  
  74.     return 0;
  75. }
  76.  
  77.  
  78.  
  79.  
  80.  
  81. void solve() {
  82.  
  83.     int n;
  84.     cin>> n;
  85.  
  86.     a.resize(n);
  87.     for(int i=0; i<n; i++) cin >> a[i];
  88.  
  89.     cout << consistency(n) << endl;
  90.  
  91.  
  92. }
  93.  
  94.  
  95.  
  96.  
  97.  
  98. int32_t main() {
  99.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  100.  
  101.     int t = 1;
  102.     // cin >> t;
  103.     while (t--) {
  104.         solve();
  105.     }
  106.  
  107.     return 0;
  108. }
Success #stdin #stdout 0s 5252KB
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https://ideone.com/c6kfPx
language:
C++14 (gcc 8.3)
created:
1 hour ago
visibility:
public

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