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  1. #include <iostream>
  2. #include<vector>
  3. #include<unordered_map>
  4. using namespace std;
  5.  
  6. int main() {
  7. 	vector<int> nums = {1,3,2,4};
  8. 	int k = 4;
  9. 	int n = nums.size();                  
  10.  
  11. 	unordered_map<int,int> m;
  12. 	vector<int> prefix(n + 1, 0);         
  13. 	int count = 0;
  14.  
  15. 	for(int i = 1; i < n; i++) {         
  16.     	prefix[i] = prefix[i-1] + nums[i];
  17. 	}
  18.  
  19. 	m[0] = 1;                             
  20.  
  21. 	for(int j = 1; j <= n; j++) {         
  22.     	int RHS = ((prefix[j] - j) % k + k) % k;      
  23.  
  24.     	count += m[RHS];
  25.  
  26.     	int LHS = ((prefix[j-1] - j) % k + k) % k;  
  27.     	m[LHS]++;
  28. 	}
  29.  
  30. 	cout << count;
  31. 	return 0;
  32. }
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/AvdHXt
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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