using System;

using System.Collections.Generic;

​

public class Program

{

    /*

    Given this matrix, a start coordinate, and an end coordinate, return the minimum number of steps required to reach the end coordinate from the start. If there is no possible path, then return null. You can move up, left, down, and right. You cannot move through walls. You cannot wrap around the edges of the board.

    */

    public class Node

    {

        public int x;

        public int y;

        public int steps;

        public Node(int x, int y, int steps)

        {

            this.x = x;

            this.y = y;

            this.steps = steps;

        }

    }

​

    public static int MinimumSteps(bool[][] matrix, int[] startPoints, int[] endPoints)

    {

        int[][] dirs = new int[][]{new int[]{1, 0}, new int[]{-1, 0}, new int[]{0, 1}, new int[]{0, -1}};

        Queue<Node> queue = new Queue<Node>();

        queue.Enqueue(new Node(startPoints[0], startPoints[1], 0));

        while (queue.Count > 0)

        {

            Node node = queue.Dequeue();

            if (node.x == endPoints[0] && node.y == endPoints[1])

                return node.steps;

            foreach (int[] dir in dirs)

            {

                int x = node.x + dir[0];

                int y = node.y + dir[1];

                if (x >= 0 && x < matrix.Length && y >= 0 && y < matrix[0].Length)

                {

                    if (matrix[x][y] == false)

                    {

                        queue.Enqueue(new Node(x, y, node.steps + 1));

                        matrix[x][y] = true;

                    }

                }

            }

        }

​

        return -1;

    }

​

    public static void Main()

    {

        Console.WriteLine(MinimumSteps(new bool[][]{new bool[]{false, false, false, false}, new bool[]{true, true, false, true}, new bool[]{false, false, false, false}, new bool[]{false, false, false, false}}, new int[]{3, 0}, new int[]{0, 0}));

    }

}