Program.cs

using System;
using System.Linq;
using System.Collections.Generic;

namespace Day10
{
    class Program
    {
        static void Main(string[] args)
        {
            List<char[]> Instructions = new List<char[]>();
            List<int> ErrorScoresPart1 = new List<int>();
            List<long> ErrorScoresPart2 = new List<long>();

            Dictionary<char, char> Delimiters = new Dictionary<char, char>() {
                { '>', '<' },
                { ')', '(' },
                { ']', '[' },
                { '}', '{' }
            };

            foreach (String line in System.IO.File.ReadLines(@"c:\Temp\day10.txt"))
            {
                Instructions.Add(line.ToCharArray());
            }

            List<char[]> IncompleteLines = new List<char[]>();

            foreach (char[] Instruction in Instructions)
            {
                Stack<char> InstructionStack = new Stack<char>();
                bool isIncorrect = false;
                foreach (char c in Instruction)
                {
                    isIncorrect = false;
                    if (c == '(' || c == '[' || c == '{' || c == '<')
                    {
                        InstructionStack.Push(c);
                    }
                    else
                    {
                        if (InstructionStack.Peek() == Delimiters[c])
                        {
                            InstructionStack.Pop();
                        }
                        else
                        {
                            isIncorrect = true;
                            switch (c)
                            {
                                case ')':
                                    ErrorScoresPart1.Add(3);
                                    break;
                                case ']':
                                    ErrorScoresPart1.Add(57);
                                    break;
                                case '}':
                                    ErrorScoresPart1.Add(1197);
                                    break;
                                case '>':
                                    ErrorScoresPart1.Add(25137);
                                    break;
                            }
                            break;
                        }
                    }
                }
                if (!isIncorrect) 
                { 
                    IncompleteLines.Add(Instruction);
                }
            }

            foreach (char[] IncompleteInstruction in IncompleteLines)
            {
                Stack<char> InstructionStack = new Stack<char>();
                long ErrorScore = 0;
                foreach (char c in IncompleteInstruction)
                {   
                    if (c == '(' || c == '[' || c == '{' || c == '<')
                    {
                        InstructionStack.Push(c);
                    }
                    else
                    {
                        if (InstructionStack.Peek() == Delimiters[c])
                        {
                            InstructionStack.Pop();
                        }
                    }
                }
                while (InstructionStack.Count > 0)
                {
                    char c1 = InstructionStack.Pop();
                    switch (c1)
                    {
                        case '(':
                            ErrorScore = (ErrorScore * 5) + 1;
                            break;
                        case '[':
                            ErrorScore = (ErrorScore * 5) + 2;
                            break;
                        case '{':
                            ErrorScore = (ErrorScore * 5) + 3;
                            break;
                        case '<':
                            ErrorScore = (ErrorScore * 5) + 4;
                            break;
                    }
                }
                ErrorScoresPart2.Add(ErrorScore);
            }
            Console.WriteLine(ErrorScoresPart1.Sum());
            Console.WriteLine(ErrorScoresPart2
                    .OrderBy(x => x)
                    .ToList()
                    .ElementAt((int)ErrorScoresPart2.Count / 2));           
        }
    }
}