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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. #define fi first
  5. #define se second
  6.  
  7. int main(void){
  8. 	ios_base::sync_with_stdio(false);
  9. 	cin.tie(NULL);
  10. 	ll n;
  11. 	cin>>n;
  12. 	vector<ll> arr(n);
  13. 	ll gcd=0;
  14. 	int flag=0,c=0;
  15. 	for(int i=0;i<n;i++) {
  16. 		cin>>arr[i];
  17. 		gcd=__gcd(gcd,arr[i]);
  18. 		if(arr[i]==1 ) {
  19. 			flag=1;
  20. 			c++;
  21. 		}
  22. 	}
  23. 	if(flag==1) cout<<n-c;
  24. 	else if(gcd>1) cout<<"-1";
  25. 	else{
  26. 		ll mincnt1=INT_MAX,mincnt2=INT_MAX;
  27. 		for(int i=0;i<n;i++){
  28. 			ll gcd1=arr[i],gcd2=arr[i],cnt1=0,cnt2=0;
  29. 			for(int j=i+1;j<n;j++){
  30. 				gcd1=__gcd(gcd1,arr[j]);
  31. 				cnt1++;
  32. 				if(gcd1==1) break;
  33. 			}
  34. 			if(cnt1>0 && gcd1==1)
  35. 			mincnt1=min(mincnt1,cnt1);
  36. 			for(int j=i-1;j>=0;j--){
  37. 				gcd2=__gcd(gcd2,arr[j]);
  38. 				cnt2++;
  39. 				if(gcd2==1) break;
  40. 			}
  41. 			if(cnt2>0 && gcd2==1)
  42. 			mincnt2=min(mincnt2,cnt2);
  43. 			//out<<cnt1<<" "<<cnt2<<endl;
  44. 		}
  45. 		cout<<n-1+min(mincnt1,mincnt2);
  46. 	}
  47. 	return 0;
  48. }
Success #stdin #stdout 0s 4552KB
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https://ideone.com/wZgBeA
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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