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  1. /*
  2.     Cred : SunnyYeahBoi
  3.     It's my last chance (⌐■_■)
  4.     Problem :
  5. */
  6.  
  7. #include<bits/stdc++.h>
  8.  
  9. using namespace std;
  10.  
  11. #define int long long
  12. #define double long double
  13. #define endl "\n"
  14. #define NAME "a"
  15.  
  16. const int MAXN = 1e6 + 5;
  17. const int inf = 1e18;
  18. const int MOD = 1e9 + 7;
  19.  
  20. void FileInput(){
  21.     if(fopen(NAME".inp" , "r") == NULL)
  22.         freopen(NAME".inp" , "w" , stdout);
  23.     freopen(NAME".inp" , "r" , stdin);
  24.     freopen(NAME".out" , "w" , stdout);
  25. }
  26.  
  27. int n , k;
  28. int a[MAXN];
  29. int pref[MAXN] , suf[MAXN];
  30.  
  31. void solve(){
  32.     cin >> n >> k;
  33.     for(int i = 1 ; i <= n ; i++) cin >> a[i];
  34.  
  35.     pref[1] = a[1]; // pref[i] - gcd(a[1] , a[2] , ... , a[i])
  36.     suf[n] = a[n]; // suf[i] - gcd(a[i] , a[i + 1] , ... , a[n])
  37.  
  38.     for(int i = 2 ; i <= n ; i++)
  39.         pref[i] = __gcd(pref[i - 1] , a[i]);
  40.     for(int i = n - 1 ; i > 0 ; i--)
  41.         suf[i] = __gcd(suf[i + 1] , a[i]);
  42.  
  43.     int res = -inf;
  44.     for(int i = 1 ; i + k - 1 <= n ; i++){
  45.         int gc = 0;
  46.  
  47.         if(i == 1)
  48.             gc = suf[i + k];
  49.         else if(i + k - 1 == n)
  50.             gc = pref[i - 1];
  51.         else gc = __gcd(pref[i - 1] , suf[i + k]);
  52.  
  53.         res = max(res , gc);
  54.     }
  55.  
  56.     cout << res << endl;
  57. }
  58.  
  59. int32_t main(){
  60.     FileInput();
  61.     ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  62.     int t = 1;
  63.     // cin >> t;
  64.     while(t--)
  65.         solve();
  66.     return 0;
  67. }
  68.  
Success #stdin #stdout 0s 5848KB
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https://ideone.com/FSn3tD
language:
C++14 (gcc 8.3)
created:
16 hours ago
visibility:
public

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