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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.  
  33. int consistency1(int n){
  34.  
  35. 	int total = 0;
  36. 	for(int i=0; i<n; i++) total += a[i];
  37.  
  38. 	if(total % 4 != 0) return false;
  39. 	int x = total/4;
  40.  
  41. 	unordered_map<int,int> prefixSum;
  42. 	unordered_map<int,int> suffixSum;
  43.  
  44. 	int sum = 0;
  45. 	for(int i=n-1; i>=2; i--){
  46. 		sum += a[i];
  47. 		suffixSum[sum]++;
  48. 	}
  49. 	prefixSum[a[0]]++;
  50.  
  51.  
  52. 	int ans = 0;
  53. 	int leftSum = a[0];
  54.  
  55.  
  56. 	for(int i=1; i<=n-2; i++){
  57.  
  58. 		leftSum += a[i];
  59. 		int rightSum = total - leftSum;
  60.  
  61. 		suffixSum[rightSum]--;
  62. 		if(suffixSum[rightSum] == 0) suffixSum.erase(rightSum);
  63.  
  64.  
  65. 		if(leftSum == 2*x && rightSum == 2*x){
  66. 			ans += prefixSum[leftSum/2] * suffixSum[rightSum/2];
  67. 		}
  68.  
  69. 		prefixSum[leftSum]++;
  70. 	}
  71.  
  72. 	return ans;
  73.  
  74. }
  75.  
  76.  
  77.  
  78.  
  79.  
  80. int consistency2(int n){
  81.  
  82. 	int total = 0;
  83. 	for(int i=0; i<n; i++) total += a[i];
  84.  
  85. 	if(total % 4 != 0) return false;
  86. 	int y = total/4;
  87.  
  88.  
  89. 	vector<int> suffixCt(n+1, 0);
  90.  
  91. 	int x = 0;
  92. 	int xx = 0;
  93. 	int sum = 0;
  94. 	for(int i=n-1; i>=0; i--){
  95. 		sum += a[i];
  96.  
  97. 		if(sum == 2*y){
  98. 			xx = x;
  99. 			suffixCt[i] = xx;
  100. 		}
  101. 		else suffixCt[i] = suffixCt[i+1];
  102.  
  103. 		if(sum == y)	x++;
  104.  
  105. 	}
  106.  
  107.  
  108. 	sum = a[0];
  109. 	x = a[0] == y ? 1 : 0;
  110. 	xx = 0;
  111.  
  112. 	int ans = 0;
  113.  
  114. 	for(int i=1; i<=n-3; i++){
  115. 		sum += a[i];
  116.  
  117. 		if(sum == 2*y){
  118. 			xx = x;
  119.  
  120. 			int leftCt = xx;
  121. 			int rightCt = suffixCt[i+1];
  122. 			ans += leftCt * rightCt;
  123. 		}
  124. 		if(sum == y) x++;
  125.  
  126. 	}
  127.  
  128. 	return ans;
  129.  
  130. }
  131.  
  132.  
  133.  
  134.  
  135.  
  136.  
  137.  
  138.  
  139.  
  140.  
  141.  
  142.  
  143.  
  144.  
  145.  
  146.  
  147.  
  148.  
  149.  
  150.  
  151.  
  152.  
  153.  
  154. int practice(int n){
  155.  
  156.  
  157.     return 0;
  158. }
  159.  
  160.  
  161.  
  162.  
  163.  
  164. void solve() {
  165.  
  166.     int n;
  167.     cin>> n;
  168.  
  169.     a.resize(n);
  170.     for(int i=0; i<n; i++) cin >> a[i];
  171.  
  172.     cout << consistency1(n) << " " << consistency2(n) << endl;
  173.  
  174.  
  175. }
  176.  
  177.  
  178.  
  179.  
  180.  
  181. int32_t main() {
  182.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  183.  
  184.     int t = 1;
  185.     cin >> t;
  186.     while (t--) {
  187.         solve();
  188.     }
  189.  
  190.     return 0;
  191. }
Success #stdin #stdout 0s 5312KB
comments (?)
stdin
copy 
3
5
0 0 0 0 0 
10
7 -2 4 -1 -3 5 -5 2 -2 -5
11
8 -3 1 -6 4 -4 7 -7 2 -2 0
stdout
copy 
4 4
0 0
4 4
https://ideone.com/jBSta2
language:
C++14 (gcc 8.3)
created:
1 hour ago
visibility:
public

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