121 lines
3.7 KiB
C#
121 lines
3.7 KiB
C#
using System;
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using static System.Console;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using Xunit;
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namespace AdventOfCode {
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public class Program {
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static string RootDir =
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Environment.GetEnvironmentVariable("HOME") + "/src/adventofcode/2020/";
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static List<int> ReadInts(string filename) {
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string[] lines = File.ReadAllLines(filename);
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return lines.Select(int.Parse).ToList();
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}
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static int Day1Part1(List<int> numbers) {
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for (var i = 0; i < numbers.Count; i++) {
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for (var j = i + 1; j < numbers.Count; j++) {
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if (numbers[i] + numbers[j] == 2020) {
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return numbers[i] * numbers[j];
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}
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}
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}
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throw new ArgumentException("no pair of numbers summed to 2020");
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}
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static int Day1Part2(List<int> numbers) {
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for (var i = 0; i < numbers.Count; i++) {
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for (var j = i + 1; j < numbers.Count; j++) {
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for (var k = j + 1; k < numbers.Count; k++) {
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if (numbers[i] + numbers[j] + numbers[k] == 2020) {
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return numbers[i] * numbers[j] * numbers[k];
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}
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}
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}
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}
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throw new ArgumentException("no triple of numbers summed to 2020");
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}
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[Fact]
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static void Day1Test() {
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var emptyInput = new List<int>();
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var bogusInput = new List<int>() {
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111, 222, 333, 444, 555, 666, 777, 888, 999
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};
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var exampleInput = new List<int>() {
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1721, 979, 366, 299, 675, 1456
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};
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var testInput = ReadInts(RootDir + "day1.txt");
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Assert.Throws<ArgumentException>(() => Day1Part1(emptyInput));
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Assert.Throws<ArgumentException>(() => Day1Part1(bogusInput));
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Assert.Equal(514579, Day1Part1(exampleInput));
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Assert.Equal(355875, Day1Part1(testInput));
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Assert.Throws<ArgumentException>(() => Day1Part2(emptyInput));
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Assert.Throws<ArgumentException>(() => Day1Part2(bogusInput));
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Assert.Equal(241861950, Day1Part2(exampleInput));
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Assert.Equal(140379120, Day1Part2(testInput));
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}
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static bool IsPasswordValid1(string spec) {
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string[] tokens = spec.Split(' ');
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string[] numbers = tokens[0].Split('-');
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int min = int.Parse(numbers[0]);
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int max = int.Parse(numbers[1]);
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char required = tokens[1][0];
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string password = tokens[2];
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int count = 0;
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for (int i = 0; i < password.Length; i++) {
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if (password[i] == required) {
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count++;
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}
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}
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return min <= count && count <= max;
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}
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static bool IsPasswordValid2(string spec) {
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string[] tokens = spec.Split(' ');
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string[] numbers = tokens[0].Split('-');
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int lowIndex = int.Parse(numbers[0]) - 1;
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int highIndex = int.Parse(numbers[1]) - 1;
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char required = tokens[1][0];
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string password = tokens[2];
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return
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(password[lowIndex] == required && password[highIndex] != required) ||
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(password[lowIndex] != required && password[highIndex] == required);
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}
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static int Day2Part1() {
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return File.ReadAllLines(RootDir + "day02.txt").Count(IsPasswordValid1);
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}
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static int Day2Part2() {
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return File.ReadAllLines(RootDir + "day02.txt").Count(IsPasswordValid2);
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}
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[Fact]
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static void Day2Test() {
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Assert.True(IsPasswordValid1("1-3 a: abcde"));
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Assert.False(IsPasswordValid1("1-3 b: cdefg"));
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Assert.True(IsPasswordValid1("2-9 c: ccccccccc"));
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Assert.Equal(603, Day2Part1());
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Assert.True(IsPasswordValid2("1-3 a: abcde"));
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Assert.False(IsPasswordValid2("1-3 b: cdefg"));
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Assert.False(IsPasswordValid2("2-9 c: ccccccccc"));
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Assert.Equal(404, Day2Part2());
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}
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static void Main(string[] args) {
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Day2Test();
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}
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}
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}
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