code: import static java.lang.Math.*;
  
  public class RayCasting {
  
      static boolean intersects(int[] A, int[] B, double[] P) {
          if (A[1] > B[1])
              return intersects(B, A, P);
  
          if (P[1] == A[1] || P[1] == B[1])
              P[1] += 0.0001;
  
          if (P[1] > B[1] || P[1] < A[1] || P[0] >= max(A[0], B[0]))
              return false;
  
          if (P[0] < min(A[0], B[0]))
              return true;
  
          double red = (P[1] - A[1]) / (double) (P[0] - A[0]);
          double blue = (B[1] - A[1]) / (double) (B[0] - A[0]);
          return red >= blue;
      }
  
      static boolean contains(int[][] shape, double[] pnt) {
          boolean inside = false;
          int len = shape.length;
          for (int i = 0; i < len; i++) {
              if (intersects(shape[i], shape[(i + 1) % len], pnt))
                  inside = !inside;
          }
          return inside;
      }
  
      public static void main(String[] a) {
          double[][] testPoints = {{10, 10}, {10, 16}, {-20, 10}, {0, 10},
          {20, 10}, {16, 10}, {20, 20}};
  
          for (int[][] shape : shapes) {
              for (double[] pnt : testPoints)
                  System.out.printf("%7s ", contains(shape, pnt));
              System.out.println();
          }
      }
  
      final static int[][] square = {{0, 0}, {20, 0}, {20, 20}, {0, 20}};
  
      final static int[][] squareHole = {{0, 0}, {20, 0}, {20, 20}, {0, 20},
      {5, 5}, {15, 5}, {15, 15}, {5, 15}};
  
      final static int[][] strange = {{0, 0}, {5, 5}, {0, 20}, {5, 15}, {15, 15},
      {20, 20}, {20, 0}};
  
      final static int[][] hexagon = {{6, 0}, {14, 0}, {20, 10}, {14, 20},
      {6, 20}, {0, 10}};
  
      final static int[][][] shapes = {square, squareHole, strange, hexagon};
  }
  