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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	static double f (double x, double x0, double x1, double y, double y0, double y1){
  11. 		return  (x - x0) * (y1 - y0) - (y - y0) * (x1 - x0);
  12. 	}
  13. 	public static void main (String[] args) throws java.lang.Exception
  14. 	{
  15. 		double xa, ya, xb, yb, xc, yc, xd, yd;
  16. 		Scanner in = new Scanner(System.in);
  17. 		xa = in.nextDouble();
  18. 		ya = in.nextDouble();
  19. 		xb = in.nextDouble();
  20. 		yb = in.nextDouble();
  21. 		xc = in.nextDouble();
  22. 		yc = in.nextDouble();
  23. 		xd = in.nextDouble();
  24. 		yd = in.nextDouble();
  25. 		double l,m;
  26. 		l = f(xc,xb,xa,yc,yb,ya);
  27. 		m = f(xd,xb,xa,yd,yb,ya);
  28. 		if (l * m < 0) {
  29. 			System.out.printf("не выпуклый");
  30. 			return;
  31. 		}
  32. 		double q,w;
  33. 		q = f(xa,xc,xb,ya,yc,yb);
  34. 		w = f(xd,xc,xb,yd,yc,yb);
  35. 		if (q * w < 0) {
  36. 			System.out.printf("не выпуклый");
  37. 			return;
  38. 		}
  39. 		double p,r;
  40. 		p = f(xa,xd,xc,ya,yd,yc);
  41. 		r = f(xb,xd,xc,yb,yd,yc);
  42. 		if (p * r < 0) {
  43. 			System.out.printf("не выпуклый");
  44. 			return;
  45. 		}
  46. 		double j,k;
  47. 		j = f(xb,xa,xd,yb,ya,yd);
  48. 		k = f(xc,xa,xd,yc,ya,yd);
  49. 		if (j * k < 0) {
  50. 			System.out.printf("не выпуклый");
  51. 			return;
  52. 		}
  53. 		System.out.printf(" Выпуклый ");
  54. 	}
  55. }
Success #stdin #stdout 0.15s 321280KB
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не выпуклый
https://ideone.com/wQKNHG
Ю2.5
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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