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  1. #include<iostream>
  2. #include<cmath>
  3. #include<vector>
  4. #include<climits>
  5. #include<algorithm>
  6. #include<numeric>
  7. #include<iomanip>
  8. #include<map>
  9. #include<unordered_map>
  10. #include<set>
  11. #include<random>
  12. #include<cassert>
  13. using namespace std;
  14. #define ll long long int
  15. #define ld long double
  16. const ll Mod = (ll)1e9+7;
  17. ll n;
  18. set<pair<ll,ll> > ss;
  19. ll M[100][100];
  20.  
  21. void f(ll x,ll y)
  22. {
  23. 	if(x>n || y>n || x<1 || y<1)
  24. 	{
  25. 	return;	
  26. 	}
  27. 	if(M[x][y]==0){return;}
  28.  
  29. 	if(M[x][y])
  30. 	{
  31. 	// can be reached
  32. 	ss.erase({x,y});	
  33.      }
  34.     M[x][y]=0 ; 
  35.  
  36. 	f(x+1,y+2);
  37. 	f(x+2,y+1);
  38. 	f(x-1,y-2);
  39. 	f(x-2,y-1);
  40. 	f(x+1,y-2);
  41. 	f(x-1,y+2);
  42. 	f(x+2,y-1);
  43. 	f(x-2,y+1);
  44.  
  45. 	M[x][y]=1;
  46. 	// to block after one call
  47.  
  48. 	return;
  49. }
  50.  
  51. int main()
  52. {
  53. 	cin>>n;
  54. 	// n*n;
  55. 	for(ll i=1;i<=n;i++)
  56. 	for(ll j=1;j<=n;j++)
  57. 	{cin>>M[i][j];
  58. 	if(M[i][j]){ss.insert({i,j}) ;}	
  59. 	}
  60.  
  61. 	f(1,1);
  62.  
  63. 	ll ans = (ll)ss.size() ;
  64. 	cout<<ans<<endl;
  65.  
  66. return 0;
  67. }
  68.  
Success #stdin #stdout 0s 4560KB
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https://ideone.com/SKojxo
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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