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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; cin>>n;
  8. 	vector<int>arr(n+1);
  9. 	for(int i =1; i<=n;i++)cin>>arr[i];
  10. 	int k ; cin>>k;
  11. 	for(int i = 1 ; i<=n;i++){
  12. 		if(arr[i]>k) arr[i]=1;
  13. 		else if(arr[i]==k) arr[i]=0;
  14. 		else{
  15. 			arr[i]=-1;
  16. 	}
  17. 	}
  18. 	unordered_map<int,int>even_count;
  19. 	unordered_map<int,int>odd_count;
  20. 	vector<int>prefix_sum(n+1);
  21. 	prefix_sum[0]=0;
  22. 	even_count[0]=1;
  23. 	int count  = 0; 
  24. 	for(int i = 1 ; i<=n;i++){
  25. 		prefix_sum[i]=prefix_sum[i-1]+arr[i];
  26. 		if(i%2==0){ 
  27. 		   count +=odd_count[prefix_sum[i]];
  28. 		   even_count[prefix_sum[i]]++;
  29. 		}
  30. 		else {
  31. 		   count +=even_count[prefix_sum[i]];
  32. 		   odd_count[prefix_sum[i]]++;
  33. 		}
  34. 		}
  35.     cout<<count;
  36. 	return 0;
  37. }
Success #stdin #stdout 0.01s 5272KB
comments (?)
stdin 
6 
5 3 1 4 7 7 
4
stdout 
4
https://ideone.com/tCxsfb
language:
C++ (gcc 8.3)
created:
7 days ago
visibility:
public

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