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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 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. int consistency2(int n){
  60.  
  61. 	int total = 0;
  62. 	for(int i=0; i<n; i++) total += a[i];
  63.  
  64. 	if(total % 3 != 0) return false;
  65. 	int x = total/3;
  66.  
  67.  
  68. 	unordered_map<int,int> prefixSum;
  69.  
  70. 	int ans = 0;
  71. 	int sum = 0;
  72.  
  73. 	for(int i=0; i<=n-2; i++){
  74. 		sum += a[i];
  75.  
  76. 		if( !(sum & 1) && sum == 2*x ){
  77. 			ans += prefixSum[sum/2];
  78. 		}
  79. 		prefixSum[sum]++;
  80. 	}
  81.  
  82. 	return ans;
  83.  
  84. }
  85.  
  86.  
  87.  
  88.  
  89.  
  90.  
  91. int consistency3(int n){
  92.  
  93. 	int total = 0;
  94. 	for(int i=0; i<n; i++) total += a[i];
  95.  
  96. 	if(total % 3 != 0) return false;
  97. 	int x = total/3;
  98.  
  99.  
  100. 	int ct = 0;
  101. 	int ans = 0;
  102. 	int sum = 0;
  103.  
  104. 	for(int i=0; i<=n-2; i++){
  105. 		sum += a[i];
  106.  
  107. 		if(sum == x ){
  108. 			ct++;
  109. 		}
  110. 		if(sum == 2*x){
  111. 			ans += ct;
  112. 		}
  113.  
  114. 	}
  115.  
  116. 	return ans;
  117.  
  118. }
  119.  
  120.  
  121.  
  122.  
  123.  
  124.  
  125.  
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  127.  
  128.  
  129.  
  130.  
  131.  
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  133.  
  134.  
  135.  
  136.  
  137.  
  138.  
  139.  
  140.  
  141.  
  142.  
  143.  
  144. int practice(int n){
  145.  
  146.  
  147.     return 0;
  148. }
  149.  
  150.  
  151.  
  152.  
  153.  
  154. void solve() {
  155.  
  156.     int n;
  157.     cin>> n;
  158.  
  159.     a.resize(n);
  160.     for(int i=0; i<n; i++) cin >> a[i];
  161.  
  162.     cout << consistency1(n) << " " << consistency2(n) << " " << consistency3(n) << endl;
  163.  
  164.  
  165. }
  166.  
  167.  
  168.  
  169.  
  170.  
  171. int32_t main() {
  172.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  173.  
  174.     int t = 1;
  175.     // cin >> t;
  176.     while (t--) {
  177.         solve();
  178.     }
  179.  
  180.     return 0;
  181. }
Success #stdin #stdout 0s 5316KB
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3 3 3
https://ideone.com/8cpMjp
language:
C++14 (gcc 8.3)
created:
1 hour ago
visibility:
public

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