Day 02 solution

2018/Day 02/Program.cs

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+using System;
+using System.IO;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Day_02
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            //Part1();
+            Part2();            
+        }
+
+        static void Part1()
+        {
+            int twiceCounter = 0; 
+            int thriceCounter = 0;
+
+            var lines = File.ReadAllLines("input.txt");
+            foreach (var line in lines)
+            {
+                List<char> searchCharHistory = new List<char>();
+                int lineTwiceCounter = 0;
+                int lineThriceCounter = 0;
+
+                for (int i = 0; i < line.Length; i++)
+                {
+                    char searchChar = line[i];
+
+                    if(!searchCharHistory.Any(s => s == searchChar))
+                    {
+                        // If we haven't already counted this letter 
+
+                        int matchCharCount = line.Count(f => f == searchChar);
+
+                        // Check if a letter appears twice (and increment the counter) 
+                        if (matchCharCount == 2) {
+                            lineTwiceCounter += 1;
+                        }
+                        // Check if a letter appears three times (and increment the counter)
+                        else if (matchCharCount == 3) {
+                            lineThriceCounter += 1;
+                        }
+                    }
+                    searchCharHistory.Add(searchChar);
+                }
+
+                if (lineTwiceCounter > 0) {
+                    twiceCounter += 1;
+                }
+                if (lineThriceCounter > 0) {
+                    thriceCounter += 1;
+                }
+            }
+            Console.WriteLine(twiceCounter);
+            Console.WriteLine(thriceCounter);
+            // multiply the two counters together 
+            Console.WriteLine("The checksum is " + (twiceCounter * thriceCounter));
+        }
+
+        static void Part2()
+        {
+            bool endLoop = false;
+
+            var lines = File.ReadAllLines("input.txt");
+            // For each line of the input file
+            for (int i = 0; i < lines.Length; i++)
+            {
+                // Compare this line with each other line in the array 
+                for (int j = 0; j < lines.Length; j++) {
+                    if (CompareStrings(lines[i],lines[j])) {
+                        // If it finds a string with just one letter wrong
+                        endLoop = true; 
+                        break;
+                    }
+                }
+                if (endLoop) {
+                    break;
+                }
+            }
+        }
+
+        static bool CompareStrings(string string1, string string2)
+        {
+            if (string1 == string2) {
+                // Do nothing, it's the same string
+            }
+            
+            // Split the characters of both strings into arrays 
+            List<char> arr1 = new List<char>();
+            List<char> arr2 = new List<char>();
+            
+            for (int ii = 0; ii < string1.Length; ii++) {
+                arr1.Add(string1[ii]);
+            }
+            for (int jj = 0; jj < string2.Length; jj++) {
+                arr2.Add(string2[jj]);
+            }
+
+            int wrongCharCounter = 0; 
+            List<char> sameChars = new List<char>();
+
+            // For each letter in the first array, check if it corresponds to the appropriate letter in the second array
+            for (int kk = 0; kk < arr1.Count(); kk++) {
+                if (arr1[kk] != arr2[kk]) {
+                    wrongCharCounter += 1;
+                }
+                else { 
+                    sameChars.Add(arr1[kk]);
+                }
+            }
+
+            if (wrongCharCounter == 1) {
+                Console.WriteLine("Common letters are: " + string.Join( ",", sameChars).Replace(",", ""));
+                return true;
+            }
+            else {
+                return false;
+            }
+        }
+    }
+}