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  1. import java.util.*;
  2. import java.lang.*;
  3.  
  4. class Main
  5. {
  6.     static class PointF {
  7.         public float x;
  8.         public float y;
  9.         public PointF(float x, float y) {this.x=x; this.y=y;}
  10.     }
  11.  
  12.     private static PointF sub(PointF a, PointF b) {
  13.         return new PointF(a.x-b.x, a.y-b.y);
  14.     }
  15.  
  16.     private static float getPerpDotProduct(final PointF p1, final PointF p2) {
  17.         return p1.x * p2.y - p1.y * p2.x;
  18.     }
  19.  
  20.     private static boolean isInside(PointF a, PointF b, PointF c, PointF p) { 
  21.         final float c1 = getPerpDotProduct(sub(a,b), sub(a,p));
  22.         final float c2 = getPerpDotProduct(sub(b,c), sub(b,p));
  23.         final float c3 = getPerpDotProduct(sub(c,a), sub(c,p));
  24.         return ((c1 >= 0 && c2 >= 0 & c3 >= 0) || (c1 <= 0 && c2 <= 0 && c3 <= 0));
  25.     }
  26.  
  27. 	public static void main (String[] args) throws java.lang.Exception
  28. 	{
  29.     PointF a = new PointF(10, 1);
  30.     PointF b = new PointF(1, 10);
  31.     PointF c = new PointF(2, 2);
  32.     PointF p1 = new PointF(3, 3);
  33.     PointF p2 = new PointF(0, 0);
  34.     System.out.println(isInside(a,b,c,p1));            
  35.     System.out.println(isInside(a,b,c,p2));            
  36. 	}
  37. }
Success #stdin #stdout 0.03s 245632KB
comments (?)
stdin 
Standard input is empty
stdout 
true
false
https://ideone.com/5dH9A
language:
Java (HotSpot 12)
created:
13 years ago
visibility:
public

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