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  1. //#include <ext/pb_ds/assoc_container.hpp> 
  2. //#include <ext/pb_ds/tree_policy.hpp> 
  3. //using namespace __gnu_pbds; 
  4. //#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
  5. #include <bits/stdc++.h>
  6. using namespace std;
  7. //#define int long long
  8. #define dd double
  9. #define ld long double
  10. #define ull unsigned long long
  11. #define yes cout << "YES\n"
  12. #define no cout << "NO\n"
  13. #define el "\n"
  14. #define Arwa ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  15. #define fix(x) cout << fixed << setprecision(x)
  16. #define all(v) v.begin(),v.end()
  17. void file() 
  18. {
  19.     #ifndef ONLINE_JUDGE
  20.         freopen("input.txt", "r", stdin);
  21.         freopen("output.txt", "w", stdout);
  22.     #endif
  23. }
  24. int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
  25. int lcm(int a, int b) { return a / gcd(a, b) * b; }
  26. bool prime(int n) {
  27.     if (n == 2) return true;
  28.     if (n % 2 == 0 || n == 1) return false;
  29.     for (int i = 3; i * i <= n; i += 2)
  30.         if (n % i == 0) return false;
  31.     return true;
  32. }
  33. //Here We Go Again
  34. int32_t main() 
  35. {
  36.     Arwa
  37.     int t=1;
  38.     //cin>>t;
  39.     while(t--) 
  40.     {
  41.       int n;
  42.       cin>>n;
  43.       int arr[n];
  44.       map<int,bool>m1,m2;
  45.       for(int i=0;i<n;i++)
  46.       cin>>arr[i];
  47.       bool f=1;
  48.       int s=0,e=n-1,sum1=0,sum2=0,mx=-1e9;
  49.       while(s<=e)
  50.       {
  51.         if(f)
  52.         {
  53.         sum1+=arr[s];
  54.         s++;
  55.         f=0;
  56.         }
  57.         else
  58.         {
  59.         sum2+=arr[e];
  60.         e--;
  61.         f=1;
  62.         }    
  63.         m1[sum1]=1;
  64.         m2[sum2]=1;
  65.         if(m2[sum1])
  66.         mx=max(mx,sum1);
  67.         if(m1[sum2])
  68.         mx=max(mx,sum2);   
  69.       }
  70.       cout<<max(mx,0)<<el;
  71.     }
  72.     return 0;
  73. }
  74.  
Success #stdin #stdout 0.01s 5292KB
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https://ideone.com/6OkTEp
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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