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  1. #include <bits/stdc++.h>
  2. #define endl '\n'
  3.  
  4. using namespace std;
  5.  
  6. const int N = 1<<17;
  7.  
  8. struct xorshift32 {
  9.     unsigned x,y,z,w;
  10.     xorshift32(): x(123456789), y(2378257), z(7777777), w(85715718) {}
  11.     unsigned next() {
  12.         unsigned t=x^(x<<11);
  13.         x=y;y=z;z=w;
  14.         return w=w^(w>>19)^t^(t>>8);
  15.     }
  16.     unsigned next(unsigned n) {
  17.         return next()%n;
  18.     }
  19.     int next(int a, int b) {
  20.         return a+next(b-a+1);
  21.     }
  22. };
  23.  
  24. int tests,current_case;
  25. int n,a[N];
  26. long long ans;
  27. xorshift32 rng;
  28.  
  29. void message(int current_case) {
  30.     //cerr<<"Case "<<current_case<<" solved!"<<endl;
  31.     fprintf(stderr, "Case %d solved!\n", current_case);
  32. }
  33.  
  34.  
  35.  
  36. int main() {
  37.     //ios_base::sync_with_stdio(false);
  38.     //cin.tie(NULL);
  39.     int i,j;
  40.  
  41.     tests=1;
  42.     //scanf("%d", &tests);
  43.     //cin>>tests;
  44.     for(current_case=1;current_case<=tests;current_case++) {
  45.         scanf("%d", &n);
  46.         for(i=1;i<=n;i++) {
  47.             scanf("%d", &a[i]);
  48.         }
  49.         sort(a+1,a+1+n);
  50.         while(clock()<=1.7*CLOCKS_PER_SEC) {
  51.             if(n>1000) {
  52.                 i=1+rng.next(n-1000,n);
  53.                 j=1+rng.next(n-1000,n-1);
  54.                 if(j>=i) ++j;
  55.                 ans=max(ans,(a[i]|a[j])*1ll*(a[i]&a[j]));
  56.             }
  57.             else {
  58.                 i=1+rng.next(1,n);
  59.                 j=1+rng.next(1,n-1);
  60.                 if(j>=i) {
  61.                     ++j;
  62.                 }
  63.                 ans=max(ans,(a[i]|a[j])*1ll*(a[i]&a[j]));
  64.             }
  65.         }
  66.         printf("%lld\n", ans);
  67.  
  68.         MESSAGE:
  69.         message(current_case);
  70.     }
  71.  
  72.     return 0;
  73. }
Runtime error #stdin #stdout 0s 3984KB
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Standard input is empty
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Standard output is empty
https://ideone.com/srbYNq
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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