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  1. #include <iostream>
  2. #include <vector>
  3. #include <complex>
  4. using namespace std;
  5. pair<int,int> dir(int d){
  6. 	d %= 4;
  7. 	return make_pair(d/2?d%2*2-1:0,d/2?0:d%2*2-1);
  8. }
  9. pair<int,int> iota(int d){
  10. 	d %= 4;
  11. 	return make_pair(d%2?0:1-d/2*2,d%2?1-d/2*2:0);
  12. }
  13. template <class T>
  14. complex<T> exp(complex<T> b, int e){
  15. 	complex<T> o(1,0);
  16. 	while(e){
  17. 		if(e%2)	o *= b;
  18. 		b *= b;
  19. 		e /= 2;
  20. 	}
  21. 	return o;
  22. }
  23. int main() {
  24. 	vector<string> v = {"left","right","up","down"};
  25. 	cout<<"i\tj"<<endl;
  26. 	for(int i=0; i<4; i++)
  27. 		cout<<dir(i).first<<'\t'<<dir(i).second<<"\td:"<<i<<'\t'<<v[i]<<endl;
  28.  
  29. 	// second approach
  30. 	vector<int> dirs={0,1,0,-1,0};
  31. 	v = {"right","down","left","up"};
  32. 	cout<<endl<<"i\tj"<<endl;
  33. 	for(int i=0; i<4; i++)
  34. 		cout<<dirs[i]<<'\t'<<dirs[i+1]<<"\td:"<<i<<'\t'<<v[i]<<endl;
  35.  
  36. 	v = {"right","up","left","down"};
  37. 	cout<<endl<<"x\ty"<<endl;	// plane change and hence sense of direction
  38. 	for(int i=0; i<4; i++)
  39. 		cout<<iota(i).first<<'\t'<<iota(i).second<<"\ti^"<<i<<'\t'<<v[i]<<endl;
  40.  
  41. 	complex<int> i(0,1);
  42. 	cout<<endl<<"(x,y)"<<endl;	// notation and sense of direction change
  43. 	for(int d=0; d<4; d++)
  44. 		cout<<exp(i,d)<<"\ti^"<<d<<'\t'<<v[d]<<endl;
  45.  
  46. 	return 0;
  47. }
Success #stdin #stdout 0s 4444KB
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stdin
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Standard input is empty
stdout
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i	j
0	-1	d:0	left
0	1	d:1	right
-1	0	d:2	up
1	0	d:3	down

i	j
0	1	d:0	right
1	0	d:1	down
0	-1	d:2	left
-1	0	d:3	up

x	y
1	0	i^0	right
0	1	i^1	up
-1	0	i^2	left
0	-1	i^3	down

(x,y)
(1,0)	i^0	right
(0,1)	i^1	up
(-1,0)	i^2	left
(0,-1)	i^3	down
https://ideone.com/CGUrP8
directions iterator up down left right
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
secret

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