Refactored to add a class and handle part 2

2018/Day 03/Claim.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+
+namespace Day_03
+{
+    public class Claim
+    {
+        public int ClaimId { get; set; }   
+        public bool CellsUsedMoreThanOnce { get; set; }
+    }
+}

2018/Day 03/Program.cs

@@ -9,15 +9,10 @@ namespace Day_03
     class Program
     {
         static void Main(string[] args)
-        {
-            Part1();
-            //Part2();            
-        }
-
-        static void Part1()
         {
             // Declare an empty 2D array with 1000x1000 cells, material[x,y] from left and top respectively
             int[,] material = new int[1000, 1000];
+            List<Claim> claims = new List<Claim>();
 
             var lines = File.ReadAllLines("input.txt");
             // For each line of the input file
@@ -56,6 +51,7 @@ namespace Day_03
                 }
             }
             
+            // Part 1
 
             // Loop through both arrays and count how many cells have a recorded overlap
             int overlapCounter = 0;
@@ -69,11 +65,64 @@ namespace Day_03
             Console.WriteLine(material[0, 0]);
             Console.WriteLine(material.Length);
             Console.WriteLine("The number of overlapping square inches is " + overlapCounter); 
-        }
 
-        static void Part2()
-        {
 
+            // Part 2 
+
+            // Loop through all claims (lines in the file) and find the one where the material is only used once in every cell
+
+            // For each line of the input file
+            foreach (var line in lines)
+            {
+                var claim = new Claim();
+                // A claim like #123 @ 3,2: 5x4 means that claim ID 123 specifies a rectangle 3 inches from the left edge, 2 inches from the top edge, 5 inches wide, and 4 inches tall.
+
+                // Remove the id number and everything prior to the left edge measurement 
+                int startIndex = line.IndexOf("@") + 1;
+                int endIndex = line.Length;
+                var lineData = line.Substring(startIndex, endIndex - startIndex);
+
+                // Store all the data 
+                Regex re0 = new Regex(@"(#(\d+))");
+                var claimIdList = re0.Matches(line);
+                string claimId = claimIdList[0].Value.Substring(1);
+                claim.ClaimId = Int32.Parse(claimId);
+
+                Regex re1 = new Regex(@"(@ [0-9]+,)");
+                var leftPositionList = re1.Matches(line);
+                string leftPosition = leftPositionList[0].Value.Substring(2, leftPositionList[0].Value.Length -1 - 2);
+
+                Regex re2 = new Regex(@"(,[0-9]+:)");
+                var topPositionList = re2.Matches(line);
+                string topPosition = topPositionList[0].Value.Substring(1, topPositionList[0].Value.Length -1 - 1);
+
+                Regex re3 = new Regex(@"(: [0-9]+x)");
+                var widthList = re3.Matches(line);
+                int width = Int32.Parse(widthList[0].Value.Substring(1, widthList[0].Value.Length -1 - 1));
+
+                Regex re4 = new Regex(@"(x[0-9]+)");
+                var lengthList = re4.Matches(line);
+                int length = Int32.Parse(lengthList[0].Value.Substring(1));
+
+                // Store data in all cells horizontally and vertically 
+                for (int i = 0; i < width; i++) {
+                    for (int j = 0; j < length; j++) {
+                        // Check how many times the cell has been used at the appropriate co-ordinates
+                        // If it has been used more than once, set CellsUsedMoreThanOnce to true
+                        if (material[(Int32.Parse(leftPosition) + i), (Int32.Parse(topPosition) + j)] > 1) 
+                        {
+                            claim.CellsUsedMoreThanOnce = true;
+                        }
+                    }
+                }
+
+                claims.Add(claim);
+            }
+
+            // Find the only claim that has no overlap 
+
+            int finalClaimId = claims.First(c => !c.CellsUsedMoreThanOnce).ClaimId;
+            Console.WriteLine("The ID of the only claim that doesn't overlap is: " + finalClaimId);
         }
     }
 }

2018/Day 03/TaskPart2.txt

@@ -0,0 +1,6 @@
+--- Part Two ---
+Amidst the chaos, you notice that exactly one claim doesn't overlap by even a single square inch of fabric with any other claim. If you can somehow draw attention to it, maybe the Elves will be able to make Santa's suit after all!
+
+For example, in the claims above, only claim 3 is intact after all claims are made.
+
+What is the ID of the only claim that doesn't overlap?