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  1. #include <iostream>
  2. int s(int a[2], int b[2], int c[2]) {
  3. 	int t = (a[0] - b[0]) * (a[1] - c[1]) - (a[0] - c[0]) * (a[1] - b[1]);
  4. 	return t < 0 ? -1 : t > 0 ? 1 : 0;
  5. }
  6. bool start(int p[5][2]) {
  7. 	int t = s(p[0], p[1], p[2]);
  8. 	if (t == 0) return false;
  9. 	for (int i = 0; i < 5; i++) {
  10. 		if (s(p[i], p[(i + 3) % 5], p[(i + 1) % 5]) != t) return false;
  11. 	}
  12. 	return true;
  13. }
  14. int main() {
  15. 	int p[][5][2] = {
  16. 		{{0,0},{1,2},{2,0},{0,1},{2,1}},
  17. 		{{0,0},{1,2},{2,0},{0,2},{2,2}},
  18. 		{{0,0},{0,1},{1,2},{2,1},{2,0}},
  19. 		{{0,0},{5,5},{0,5},{1,0},{1,6}},
  20. 	};
  21. 	for (int i = 0; i < sizeof p / sizeof p[0]; i++) {
  22. 		std::cout << (start(p[i]) ? "true" : "false") << std::endl;
  23. 	}
  24. 	return 0;
  25. }
  26.  
Success #stdin #stdout 0s 4200KB
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Standard input is empty
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https://ideone.com/NR1SvA
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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