Adventofcode Day 2 - Challenge 2

adventofcode-day2-2.cs

/*
The document goes on to explain that each button to be pressed can be found by starting on the previous button 
and moving to adjacent buttons on the keypad: U moves up, D moves down, L moves left, and R moves right. 
Each line of instructions corresponds to one button, starting at the previous button 
(or, for the first line, the "5" button); press whatever button you're on at the end of each line. 
If a move doesn't lead to a button, ignore it.
*/

using System;
using System.Collections.Generic;

namespace ConsoleApplication
{
    public class Program
    {
        private static string keyinstructions = @"LRULLRLDUUUDUDDDRLUDRDLDDLUUDLDDLRDRLDRLLURRULURLDRLDUDURLURRULLDDDUDDRRRDLRRDDLDURDULLRDLLLDRDLLDULDUDLLDLDRUDLLDLDDRRRDRLUDRDDLUDRRDUDUDLLDDUUDLRDUDRRUDUDRULRULUDRUUDLDLULLRLDLDDRULLRLLLULUULDURURLUUULDURLDDDURRUUDURDDDULDLURLRDRURDRUDRLLDLDRUURLLLRDRURUDLRLUDULLDDURLRURDLRDUUURRLULRRLDDULUUURLRRRLLLLLURDDRUULUDRRRUDDLLULRRUULDRDDULRLDDDRRUULUDRLRUDURUUULDLDULUUDURLLLRRDDRDLURDDDLDDDLRDRLDDURLRLLRUDRRLLDDDDDURDURRDDULDULLRULDRUURDRRDUDDUDDDDRRDULDUURDRUDRLDULRULURLLRRDRDRDLUUDRRLRLDULDDLUUUUUURRLRRRULLDDDRLRDRRRRRRRDUUDLLUDURUDDLURRUDL
UDUUURRLRLLDDRRDRRRLDDDLURURLLUDDRLUUDRRRDURRLLRURDLLRRDUUDDDDRDRURRLLLLURDLRRRULLLDLLLUDDLDRRRDLDUUDDRDUDDUURDDLULULDURDURDRUULURURRURDUURUDRRUDRLLLLRRDLLDRDDRLLURDDDUDUDUDRUURDDRUURDLRUUDDRDUURUDDLLUURDLUDRUUDRRDLLUUURDULUULDUUDLLULUUDLUDRUUDUUURLDDDRLRURDDULLRDRULULUDLUUDDDUUDLDUUDRULLDUURDDRUDURULDRDDLRUULRRRDLDLRDULRDDRLLRRLURDLDRUDLRLUDLRLDLDURRUULRLUURDULDRRULLRULRDLLDLDUDRUDDUDLDDURDDDRDLUDRULRUULLRURLDDDRDLRRDRULURULDULRDLDULDURDRDRDRDURDRLUURLRDDLDDRLDDRURLLLURURDULDUDDLLUURDUUUDRUDDRDLDRLRLDURRULDULUUDDLRULDLRRRRDLLDRUUDRLLDLUDUULRDRDLRUUDLRRDDLUULDUULRUDRURLDDDURLRRULURR
LDURLLLRLLLUURLLULDLRLLDLURULRULRDUDLDDUDRLRRDLULLDDULUUULDRLDURURLURLDLRUDULLLULDUURLLRDLUULRULLLULRDRULUDLUUULDDURLUDDUDDRDLDRDRUDLUURDDLULDUULURLUULRDRDLURUDRUDLDRLUUUUULUDUDRRURUDRULDLDRDRLRURUUDRDLULLUDLLRUUDUUDUDLLRRRLDUDDDRDUDLDLLULRDURULLLUDLLRUDDUUDRLDUULLDLUUDUULURURLLULDUULLDLUDUURLURDLUULRRLLRUDRDLLLRRRLDDLUULUURLLDRDLUUULLDUDLLLLURDULLRUDUUULLDLRLDRLLULDUDUDRULLRRLULURUURLRLURRLRRRDDRLUDULURUDRRDLUDDRRDRUDRUDLDDRLRDRRLDDRLLDDDULDLRLDURRRRRULRULLUUULUUUDRRDRDRLLURRRRUULUDDUDDDLDURDRLDLLLLLRDUDLRDRUULU
URURRUUULLLLUURDULULLDLLULRUURRDRRLUULRDDRUDRRDUURDUDRUDDRUULURULDRLDRDDDLDLRLUDDRURULRLRLLLDLRRUDLLLLRLULDLUUDUUDRDLRRULLRDRLRLUUDDRRLLDDRULLLRLLURDLRRRRRLLDDRRDLDULDULLDLULLURURRLULRLRLLLLURDDRDDDUUDRRRDUUDDLRDLDRRLLRURUDUUUDLDUULLLRLURULRULRDRLLLDLDLRDRDLLLRUURDDUDDLULRULDLRULUURLLLRRLLLLLLRUURRLULRUUUDLDUDLLRRDDRUUUURRRDRRDULRDUUDULRRRDUUUUURRDUURRRRLDUDDRURULDDURDDRDLLLRDDURUDLLRURLRRRUDDLULULDUULURLUULRDLRDUDDRUULLLRURLDLRRLUDLULDRLUDDDRURUULLDLRLLLDULUDDRLRULURLRDRRDDLDLURUDDUUURRDDLUDDRDUULRRDLDRLLLULLRULRURULRLULULRDUD
RUDLLUDRRDRRLRURRULRLRDUDLRRLRDDUDRDLRRLLRURRDDLRLLRRURULRUULDUDUULDULDLRLRDLRDLRUURLDRLUDRRDDDRDRRRDDLLLRRLULLRRDDUDULRDRDUURLDLRULULUDLLDRUDUURRUDLLRDRLRRUUUDLDUDRRULLDURRDUDDLRURDLDRLULDDURRLULLRDDDRLURLULDLRUDLURDURRUDULDUUDLLLDDDUUURRRDLLDURRDLULRULULLRDURULLURDRLLRUUDDRRUDRDRRRURUUDLDDRLDRURULDDLLULULURDLDLDULLRLRDLLUUDDUDUDDDDRURLUDUDDDRRUDDLUDULLRDLDLURDDUURDLRLUUDRRULLRDLDDDLDULDUDRDUUULULDULUDLULRLRUULLDURLDULDRDLLDULLLULRLRD";
        public static void Main(string[] args)
        {
            var keypad = new string[,]{
                {"","","1","",""},
                {"","2","3","4",""},
                {"5","6","7","8","9"},
                {"","A","B","C",""},
                {"","","D","",""},
            };
            
            var currentPosition = new int[]{1,1};
            var buttonPresses = new List<string>();

            foreach (var line in keyinstructions.Split(new string[] { Environment.NewLine }, StringSplitOptions.None))
            {
                var passingThroughPosition = new [] { currentPosition[0], currentPosition[1] };
                foreach(var instruction in line){
                    passingThroughPosition = CalculateMove(instruction, keypad, passingThroughPosition);
                }
                // take last passingThroughPosition as the final button on this line of instructions
                currentPosition = passingThroughPosition;
                // record for use later
                buttonPresses.Add(IdentifyButtonFromPosition(currentPosition, keypad));
            }
            // write out instructions
            Console.WriteLine(String.Join(", ", buttonPresses.ToArray()));
        }

        private static string IdentifyButtonFromPosition(int[] position, string[,] keypad){
            return keypad[position[0], position[1]];
        }

        private static int[] CalculateMove(char instruction, string[,] keypad, int[] currentPosition){
            var newPosition = new [] { currentPosition[0], currentPosition[1] };
            switch (instruction.ToString())
            {
                case "U":
                    newPosition[0] = newPosition[0] - 1;
                    break;
                case "D":
                    newPosition[0] = newPosition[0] + 1;
                    break;
                case "L":
                    newPosition[1] = newPosition[1] - 1;
                    break;
                case "R":
                    newPosition[1] = newPosition[1] + 1;
                    break;                                                       
                default:
                    break;
            }
            if(IsValidPosition(newPosition, keypad)){
                return newPosition;
            }
            return currentPosition;
        }

        private static bool IsValidPosition(int[] newPosition, string[,] keypad){
            if(newPosition[0] < 0 || newPosition[1] < 0) return false;
            if(newPosition[0] >= keypad.GetLength(0)) return false;
            if(newPosition[1] >= keypad.GetLength(1)) return false;
            if(IdentifyButtonFromPosition(newPosition,keypad).Length==0) return false;
            return true;
        }
    }
}