Thread: dogs chasing cats up trees

Look again at Itsme86's post (#3 in this thread)

Use the distance formula: distance = sqrt( (x1-x2)^2 + (y1-y2)^2) )

Good old Pythagoras!

Using your sample data I was able to whip up a quick program that spit this out:
Code:

Cat is at: (2,2)
Dog is at: (1,1)
There are 4 trees: (0,1) (1.5,1.5) (2.5,2.9) (0,0.5)
The closest tree to the cat is: (1.5,1.5)
The dog is 1.4142135623731 units from the cat.
The cat is 0.707106781186548 units from the closest tree.
The cat will not escape from the dog.

Since I wrote it in C# because this is the C# forum, but you need to write it in C, I guess there's no harm in posting the code to see how I did it:

Code:

(In C#)
    class Program
    {
        struct Point
        {
            double X;
            double Y;

            public Point(double x, double y)
                : this()
            {
                X = x;
                Y = y;
            }

            public double DistanceFrom(Point other)
            {
                return Math.Sqrt(Math.Pow(X - other.X, 2) + Math.Pow(Y - other.Y, 2));
            }

            public static Point FromLine(string line)
            {
                string[] parts = line.Split(' ');
                return new Point(double.Parse(parts[0]), double.Parse(parts[1]));
            }

            public override string ToString()
            {
                return "(" + X + "," + Y + ")";
            }
        }

        static void Main(string[] args)
        {
            TextReader reader = new StreamReader("..\\CatAndDog.dat");

            Point cat = Point.FromLine(reader.ReadLine());
            Point dog = Point.FromLine(reader.ReadLine());

            int numTrees = int.Parse(reader.ReadLine());
            Point[] trees = new Point[numTrees];
            for (int i = 0; i < numTrees; ++i)
                trees[i] = Point.FromLine(reader.ReadLine());
            reader.Close();

            Console.WriteLine("Cat is at: {0}", cat);
            Console.WriteLine("Dog is at: {0}", dog);
            Console.Write("There are {0} trees:", trees.Length);
            foreach (Point tree in trees)
                Console.Write(" {0}", tree);
            Console.WriteLine();

            Point closestTree = trees.OrderBy(t => t.DistanceFrom(cat)).First();
            Console.WriteLine("The closest tree to the cat is: {0}", closestTree);
            Console.WriteLine("The dog is {0} units from the cat.", dog.DistanceFrom(cat));
            Console.WriteLine("The cat is {0} units from the closest tree.", cat.DistanceFrom(closestTree));
            Console.WriteLine("The cat will{0} escape from the dog.", (cat.DistanceFrom(closestTree) * 2 < dog.DistanceFrom(cat)) ? "" : " not");
        }
    }

Then work to figure out the distance between two points, using the distance formula. That's really the key part to this.

After that, put the other points (the locations of the cat and trees and dog, into a small array of struct point {int x; int y;}, and find all the distances you need of cat to the trees, to get to the smallest distance.

You need a little algebra to work with the distance formula, and a little programming skill to get the array of structs, but that's not all that hard. Work it through by hand with a calculator, and you'll see what I mean.

Once you get the above done, the actual "can the dog catch the cat?" question, is easily answered with
Distance = rate * time

and we can help you with that, if you need it.

This thread will end with someone doing all the work for him...
To hell with the board rules right?

I've seen these types since school. Lazyness is deeply ingrained in me as one of the most detestable traits. What this person is doing, because I do prefer (I will never claim to be a fair person) to see the worst in people like this, is taking advantage of the goodwill of others and bending the board rules by baking half-assed attempts that are nothing more than verbatim copies of previously shown code, and that instantly turn into complete and valid code by someone else. Step by step this lazy arse is getting his way amidst "do it for me" posts.

But you are probably right. It's none of my business. Happy coding.

Over and out.

Originally Posted by Mario F.

This thread will end with someone doing all the work for him...
To hell with the board rules right?

By "someone" you of course mean Adak. He will gleefully provide anyone with the full code to any question they ask, without requiring any effort on their part.

Originally Posted by Adak

Did Sadam post up code for this, or not? Yes he did.

No he didn't! Read the thread!

Honestly, if it was up to me, I would ban people for doing homework for others. He didn't do anything in this thread. But it doesn't matter, and it doesn't matter how many times we yell at Adak, he's still going to do their entire program for them. Every single time. (Yes, Adak, that means you. I would have perma-banned you the first week you were here, because no matter how many times we tell you to knock it off, you ignore the homework policy, and do everyone's work for them EVERY SINGLE TIME.)


Quzah.

I changed my mind - this thread is the bloated going nowhere thread.

Further replies and actual help (no spoon-feeding) here please.
The cats, dogs and trees game