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2019 Day 03 solution
This commit is contained in:
Josh Creek
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>netcoreapp2.2</TargetFramework>
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<RootNamespace>Day_03</RootNamespace>
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</PropertyGroup>
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</Project>
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using System;
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using System.IO;
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using System.Collections.Generic;
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using System.Linq;
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namespace Day_03
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{
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class Program
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{
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static void Main(string[] args)
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{
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//Part1();
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Part2();
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}
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public class WireTouchPoint
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{
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public int x { get; set; }
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public int y { get; set; }
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}
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static List<WireTouchPoint> FindAllWireTouchPoints(List<string> wireCommands)
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{
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List<WireTouchPoint> touchPoints = new List<WireTouchPoint>(){};
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int currentX = 0;
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int currentY = 0;
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WireTouchPoint initialWTP = new WireTouchPoint();
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initialWTP.x = currentX;
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initialWTP.y = currentY;
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touchPoints.Add(initialWTP);
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// For each command, record every co-ordinate the wire touches
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foreach(string wireCommand in wireCommands)
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{
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// Not bothering with error catching for converting strings to ints as the data cannot be wrongly typed in the input file
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int distance = System.Convert.ToInt32(wireCommand.Substring(1));
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// Handle the different commands in the first letter of each command string
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switch (wireCommand[0])
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{
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case 'U':
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// Up
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for(int i = 0; i < distance; i++)
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{
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currentY += 1;
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WireTouchPoint wtp = new WireTouchPoint();
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wtp.x = currentX;
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wtp.y = currentY;
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touchPoints.Add(wtp);
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}
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break;
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case 'D':
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// Down
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for(int i = 0; i < distance; i++)
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{
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currentY -= 1;
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WireTouchPoint wtp = new WireTouchPoint();
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wtp.x = currentX;
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wtp.y = currentY;
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touchPoints.Add(wtp);
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}
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break;
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case 'L':
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// Left
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for(int i = 0; i < distance; i++)
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{
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currentX -= 1;
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WireTouchPoint wtp = new WireTouchPoint();
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wtp.x = currentX;
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wtp.y = currentY;
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touchPoints.Add(wtp);
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}
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break;
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case 'R':
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// Right
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for(int i = 0; i < distance; i++)
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{
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currentX += 1;
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WireTouchPoint wtp = new WireTouchPoint();
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wtp.x = currentX;
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wtp.y = currentY;
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touchPoints.Add(wtp);
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}
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break;
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default:
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break;
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}
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}
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return touchPoints;
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}
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internal class WireTouchPointComparer : IEqualityComparer<WireTouchPoint>
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{
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public bool Equals(WireTouchPoint wtp1, WireTouchPoint wtp2)
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{
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if(wtp1.x == wtp2.x && wtp1.y == wtp2.y)
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{
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return true;
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}
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return false;
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}
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// public int GetHashCode(WireTouchPoint obj)
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// {
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// return obj.x.GetHashCode();
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// }
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public int GetHashCode(WireTouchPoint obj)
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{
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unchecked
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{
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int hash = 17;
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hash = hash * 23 + obj.x.GetHashCode();
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hash = hash * 23 + obj.y.GetHashCode();
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return hash;
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}
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}
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}
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static void Part1()
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{
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// Each line is one wire's path trace
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var wire1 = File.ReadAllLines("input.txt")[0];
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var wire2 = File.ReadAllLines("input.txt")[1];
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List<string> wire1Commands = wire1.Split(',').ToList();
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List<string> wire2Commands = wire2.Split(',').ToList();
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// Find all points each wire touches
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List<WireTouchPoint> wire1TouchPoints = FindAllWireTouchPoints(wire1Commands);
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List<WireTouchPoint> wire2TouchPoints = FindAllWireTouchPoints(wire2Commands);
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// Find all points where the two wires cross
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var crossingPoints = wire1TouchPoints.Intersect(wire2TouchPoints, new WireTouchPointComparer()).Where(cp => cp.x != 0 && cp.y != 0);
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// Declare a large default shortest distance, probably should be setting as null and null-checking later but multitasking while writing this so cba
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int shortestManhattanDistance = 9999999;
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// For each crossing point, work out the Manhattan distance to the central port
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foreach(WireTouchPoint crossingPoint in crossingPoints)
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{
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// Convert co-ordinates to be positive numbers for calculating distance
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int xVal = crossingPoint.x > 0 ? crossingPoint.x : crossingPoint.x * -1;
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int yVal = crossingPoint.y > 0 ? crossingPoint.y : crossingPoint.y * -1;
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int manhattanDistance = (xVal - 0) + (yVal - 0);
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// Work out if it is shorter than the previously found one
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if(manhattanDistance < shortestManhattanDistance)
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{
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shortestManhattanDistance = manhattanDistance;
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}
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}
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Console.WriteLine("Part 1: The Manhattan distance from the central port to the closest intersection is " + shortestManhattanDistance);
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}
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static void Part2()
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{
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// Each line is one wire's path trace
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var wire1 = File.ReadAllLines("input.txt")[0];
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var wire2 = File.ReadAllLines("input.txt")[1];
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List<string> wire1Commands = wire1.Split(',').ToList();
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List<string> wire2Commands = wire2.Split(',').ToList();
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// Find all points each wire touches
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List<WireTouchPoint> wire1TouchPoints = FindAllWireTouchPoints(wire1Commands);
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List<WireTouchPoint> wire2TouchPoints = FindAllWireTouchPoints(wire2Commands);
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// Find all points where the two wires cross
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var crossingPoints = wire1TouchPoints.Intersect(wire2TouchPoints, new WireTouchPointComparer()).Where(cp => cp.x != 0 && cp.y != 0);
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// Declare a large default minimum steps, probably should be setting as null and null-checking later but multitasking while writing this so cba
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int minimumSteps = 9999999;
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foreach(WireTouchPoint crossingPoint in crossingPoints)
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{
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// Calculate the number of steps each wire takes to reach each the intersection
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// If a wire visits a position on the grid multiple times, use the steps value from the first time it visits that position when calculating the total value of a specific intersection.
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// The number of steps a wire takes is the total number of grid squares the wire has entered to get to that location, including the intersection being considered.
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// Calculate the minimum number of steps each wire takes to reach the crossing point (using the index rather than index + 1 as the lists are zero-indexed ordered by the route taken but we want to ignore the start co-ordinates) - this will always return the first (i.e. closest) index
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int steps1 = wire1TouchPoints.FindIndex(tp => tp.x == crossingPoint.x && tp.y == crossingPoint.y);
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int steps2 = wire2TouchPoints.FindIndex(tp => tp.x == crossingPoint.x && tp.y == crossingPoint.y);
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int totalSteps = steps1 + steps2;
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// Work out if it is fewer steps than the previously found one
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if(totalSteps < minimumSteps)
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{
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minimumSteps = totalSteps;
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}
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}
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Console.WriteLine("Part 2: The fewest combined steps the wires must take to reach an intersection is " + minimumSteps);
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}
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}
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}
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--- Day 3: Crossed Wires ---
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The gravity assist was successful, and you're well on your way to the Venus refuelling station. During the rush back on Earth, the fuel management system wasn't completely installed, so that's next on the priority list.
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Opening the front panel reveals a jumble of wires. Specifically, two wires are connected to a central port and extend outward on a grid. You trace the path each wire takes as it leaves the central port, one wire per line of text (your puzzle input).
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The wires twist and turn, but the two wires occasionally cross paths. To fix the circuit, you need to find the intersection point closest to the central port. Because the wires are on a grid, use the Manhattan distance for this measurement. While the wires do technically cross right at the central port where they both start, this point does not count, nor does a wire count as crossing with itself.
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For example, if the first wire's path is R8,U5,L5,D3, then starting from the central port (o), it goes right 8, up 5, left 5, and finally down 3:
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...........
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...........
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...........
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....+----+.
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....|....|.
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....|....|.
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....|....|.
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.........|.
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.o-------+.
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...........
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Then, if the second wire's path is U7,R6,D4,L4, it goes up 7, right 6, down 4, and left 4:
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...........
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.+-----+...
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.|.....|...
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.|..+--X-+.
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.|..|..|.|.
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.|.-X--+.|.
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.|..|....|.
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.|.......|.
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.o-------+.
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...........
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These wires cross at two locations (marked X), but the lower-left one is closer to the central port: its distance is 3 + 3 = 6.
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Here are a few more examples:
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R75,D30,R83,U83,L12,D49,R71,U7,L72
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U62,R66,U55,R34,D71,R55,D58,R83 = distance 159
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R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51
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U98,R91,D20,R16,D67,R40,U7,R15,U6,R7 = distance 135
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What is the Manhattan distance from the central port to the closest intersection?
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--- Part Two ---
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It turns out that this circuit is very timing-sensitive; you actually need to minimize the signal delay.
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To do this, calculate the number of steps each wire takes to reach each intersection; choose the intersection where the sum of both wires' steps is lowest. If a wire visits a position on the grid multiple times, use the steps value from the first time it visits that position when calculating the total value of a specific intersection.
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The number of steps a wire takes is the total number of grid squares the wire has entered to get to that location, including the intersection being considered. Again consider the example from above:
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...........
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.+-----+...
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.|.....|...
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.|..+--X-+.
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.|..|..|.|.
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.|.-X--+.|.
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.|..|....|.
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.|.......|.
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.o-------+.
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...........
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In the above example, the intersection closest to the central port is reached after 8+5+5+2 = 20 steps by the first wire and 7+6+4+3 = 20 steps by the second wire for a total of 20+20 = 40 steps.
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However, the top-right intersection is better: the first wire takes only 8+5+2 = 15 and the second wire takes only 7+6+2 = 15, a total of 15+15 = 30 steps.
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Here are the best steps for the extra examples from above:
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R75,D30,R83,U83,L12,D49,R71,U7,L72
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U62,R66,U55,R34,D71,R55,D58,R83 = 610 steps
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R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51
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U98,R91,D20,R16,D67,R40,U7,R15,U6,R7 = 410 steps
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What is the fewest combined steps the wires must take to reach an intersection?
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@@ -0,0 +1,2 @@
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R1008,U336,R184,D967,R451,D742,L235,U219,R57,D439,R869,U207,L574,U670,L808,D675,L203,D370,L279,U448,L890,U297,R279,D613,L411,D530,L372,D88,R986,U444,R319,D95,L385,D674,R887,U855,R794,U783,R633,U167,L587,D545,L726,D196,R681,U609,R677,U881,R153,D724,L63,U246,R343,U315,R580,U872,L516,U95,R463,D809,R9,U739,R540,U670,L434,D699,L158,U47,L383,D483,L341,U61,R933,D269,R816,D589,R488,D169,R972,D534,L995,D277,L887,D657,R628,D322,R753,U813,L284,D237,R676,D880,L50,D965,L401,D619,R858,U313,L156,U535,R664,U447,L251,U168,L352,U881,L734,U270,L177,D903,L114,U998,L102,D149,R848,D586,L98,D157,R942,U496,R857,U362,R398,U86,R469,U358,L721,D631,R176,D365,L112,U472,L557,D153,R97,D639,L457,U566,R570,U106,R504,D292,L94,U499,R358,U653,L704,D627,R544,D24,L407,U513,R28,U643,L510,U579,R825,D376,L867,U999,R134,D734,R654,D989,L920,U872,R64,U626,R751,D425,R620,U274,L471,D83,R979,U577,L43,D320,R673,D187,R300,U134,L451,D717,R857,U576,R570,U988,R745,U840,R799,U809,R573,U354,L208,D976,L417,U473,L555,U563,L955,U823,R712,D869,L145,D735,L780,D74,R421,U42,L158,U689,R718,D455,L670,U128,L744,U401,R149,U102,L122,U832,R872,D40,R45,D325,L553,U980,L565,D497,L435,U647,L209,D822,L593,D28,R936,U95,R349,U511,L243,U895,R421,U336,L986,U264,R376,D183,R480,D947,R416,D706,R118,D799,R424,D615,R384,U185,L338,U14,R576,D901,L734,D417,L62,D254,R784,D973,R987,D848,R32,D72,L535,D633,L668,D664,R308,D474,L418,D39,L473,U388,L518,D544,R118,D948,L844,D956,R605,U14,L948,D78,L689,U443,L996,U932,R81,D879,R556,D633,R131
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L993,U227,L414,U228,L304,U53,R695,U765,R162,D264,L530,U870,R771,D395,R27,D200,L235,D834,L559,D128,R284,U912,L959,U358,R433,U404,L539,U799,R271,D734,L104,U261,R812,D15,L474,U887,R606,U366,L694,U156,R385,D667,L329,D434,R745,U776,L319,U756,R208,D457,R705,U999,R284,U98,L657,U214,R639,D937,R675,U444,L891,D587,L914,D4,R294,D896,R534,D584,L887,U878,L807,U202,R505,U234,L284,D5,R667,U261,L127,D482,R777,D223,L707,D468,L606,U345,L509,D967,R437,U995,R28,D376,L2,D959,L814,U702,L38,D154,L79,D439,L259,U143,L376,U700,R894,U165,L300,D58,R631,D47,R684,U935,R262,D857,R797,D599,L705,U792,R439,D444,R398,D887,L81,D40,R671,U332,L820,U252,R691,U412,L794,D661,R810,U157,R858,U566,R892,D543,R10,D725,L653,D812,R733,D804,R816,U862,R994,U221,L33,U271,R766,D591,R575,D970,R152,D693,L916,U404,L658,D847,L605,D433,L583,U587,L129,D103,R407,U780,L901,D676,L846,D687,L9,D47,R295,D597,L808,U134,L186,D676,L62,U305,L73,D369,L468,U30,L472,U280,L413,U961,L98,D966,R308,D178,L21,D789,L871,D671,R665,U927,L906,U633,L135,D894,R110,D205,R324,D665,R143,D450,L978,U385,R442,D853,L518,U542,R211,U857,R119,D872,L246,U380,L874,U463,R153,U982,R832,D784,L652,U545,R71,U386,R427,D827,R986,U870,R959,U232,R509,U675,R196,U389,R944,U149,R152,U571,R527,U495,L441,U511,L899,D996,L707,D455,L358,D423,L14,D427,R144,D703,L243,U157,R876,D538,R26,D577,L385,U622,L149,D852,L225,U475,L811,D520,L226,U523,L338,D79,R565,U766,L609,U496,L189,D446,R63,U396,L629,U312,L841,D639,R466,U808,L60,D589,L146,U114,R165,U96,L809,D704,L61
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