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  1. #include <bits/stdc++.h>
  2. #include <ext/pb_ds/assoc_container.hpp>
  3. #include <ext/pb_ds/tree_policy.hpp>
  4. #define all(x) (x).begin(), (x).end()
  5. #define pb push_back
  6. using namespace std;
  7. using namespace __gnu_pbds;
  8. typedef long long ll;
  9. template <typename T>
  10. using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
  11.  
  12.  
  13. void solve() {
  14.     ll n;
  15.     cin >> n;
  16.     vector<ll> a(n);
  17.     ll ans = 0;
  18.  
  19.     for (ll i = 0; i < n; i++) {
  20.         cin >> a[i];
  21.         ans ^= a[i];
  22.     }
  23.     vector<ll> xorr(n + 1);
  24.     xorr[0] = 0;
  25.     for (ll i = 1; i <= n; i++) {
  26.         xorr[i] = i ^ xorr[i - 1];
  27.     }
  28.  
  29.  
  30.     for (ll i =  1 ; i<= n; i++) {
  31.       //  ll diff = n-i ;
  32.         //if (diff&1) ans^=i;
  33.         ll nb=n/i  , MOD = n%i;
  34.         if (nb&1) ans^=xorr[i-1];
  35.         ans^=xorr[MOD];
  36.  
  37.     }
  38.  
  39.  
  40.     cout << ans << endl;
  41. }
  42.  
  43. int main() {
  44.     ios_base::sync_with_stdio(false);
  45.     cin.tie(NULL);
  46.     ll t = 1;
  47.     //cin >> t;
  48.  
  49.     while (t--) solve();
  50.     return 0;
  51. }
Success #stdin #stdout 0s 5288KB
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https://ideone.com/9y0KJA
language:
C++ (gcc 8.3)
created:
30 days ago
visibility:
public

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