//ProjectEuler/Java/Problem15.java
//Matthew Ellison
// Created: 03-04-19
//Modified: 03-28-19
//How many routes from the top left corner to the bottom right corner are there through a 20×20 grid if you can only move right and down?
//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/JavaClasses
//This program has not been tested fully and has not even been run to completion because of the long time it takes to run
/*
	Copyright (C) 2019  Matthew Ellison

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/


import mattrixwv.Stopwatch;


public class Problem15{
	private static final Integer WIDTH = 20;
	private static final Integer LENGTH = 20;
	public static void main(String[] argv){
		Stopwatch timer = new Stopwatch();	//Used to determine the algorithm's run time

		//Setup the rest of the variables
		Long numOfRoutes = 0L;	//The number of routes from 0, 0, to 20, 20
		Integer currentX = 0;	//The current x location on the grid
		Integer currentY = 0;	//The current y location on the grid

		//Start the timer
		timer.start();

		//We write this as a recursive function
		//When in a location it always moves right first, then down
		move(currentX, currentY, numOfRoutes);

		//Stop the timer
		timer.stop();

		//Print the results
		System.out.println("The number of routes is " + numOfRoutes.toString());
		System.out.println("It took " + timer.getStr() + " to run this algorithm");
	}
	//This function acts as a handler for moving the position on the grid and counting the distance
	//It moves right first, then down
	private static void move(Integer currentX, Integer currentY, Long numOfRoutes){
		//Check if you are at the end and act accordingly
		if((currentX == WIDTH) && (currentY == LENGTH)){
			++numOfRoutes;
			return;
		}

		//Move right if possible
		if(currentX < WIDTH){
			move(currentX + 1, currentY, numOfRoutes);
		}

		//Move down if possible
		if(currentY < LENGTH){
			move(currentX, currentY + 1, numOfRoutes);
		}
	}
}

/* Results:

*/