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  1. #include <iostream>
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5. int main() {
  6. 	// your code goes here
  7. 	int n;
  8. 	cin>>n;
  9. 	vector<int> arr(n);
  10. 	int tot=0;
  11. 	for(int i=0;i<n;i++){
  12. 		cin>>arr[i];
  13. 		tot=tot+arr[i];
  14. 	}
  15.  
  16. 	vector<int> prefix(n);
  17. 	vector<int> suffix(n);
  18. 	int cnt=0;int s=0;
  19.  
  20.  
  21. 	for(int i=0;i<n;i++){
  22. 		s = s + arr[i];
  23. 		if(s==tot/4){
  24. 			cnt++;
  25. 		}
  26. 		prefix[i]=cnt;
  27. 	}
  28. 	cnt=0;
  29. 	s=0;
  30.  
  31. 	for(int i=n-1;i>=0;i--){
  32. 			s = s + arr[i];
  33. 		if(s==tot/4){
  34. 			cnt++;
  35. 		}
  36. 		suffix[i]=cnt;
  37. 	}
  38. 	int ans=0;
  39.  
  40. 	if(tot%4!=0){
  41. 		cout<<"Not possible";
  42. 	}
  43. 	else{
  44. 		int sum=0;
  45.  
  46. 		for(int i=0;i<n;i++){
  47. 			sum=sum+arr[i];
  48. 			if(sum==tot/2){
  49. 				ans=ans+prefix[i]*suffix[i+1];
  50.  
  51.  
  52. 			}
  53. 		}
  54. 		cout<<ans<<endl;
  55.  
  56. 	}
  57.  
  58.  
  59.  
  60. 	return 0;
  61. }
Success #stdin #stdout 0.01s 5296KB
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https://ideone.com/1ACgA4
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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