Day6 solution
login000
parent
654f7d946b
commit
90aa8db5aa
|
|
@ -0,0 +1,257 @@
|
|||
using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Linq;
|
||||
using System.Reflection.Emit;
|
||||
using System.Text;
|
||||
using System.Threading.Tasks;
|
||||
using System.Text.RegularExpressions;
|
||||
using System.IO.Compression;
|
||||
using System.Xml.Serialization;
|
||||
|
||||
namespace Advent24
|
||||
{
|
||||
internal class Day6
|
||||
{
|
||||
private static Boolean simulateGuardPath(String map, ref HashSet<Int32> visited, Int32 newObstacleLinearPosition = -1)
|
||||
{
|
||||
// get width of line to be able to navigate the text block in
|
||||
// both dimensions
|
||||
Int32 mapWidth = map.IndexOf('\n');
|
||||
|
||||
Int32 guardLinearPosition = 0;
|
||||
Int32 guardDirection = 0; //1 = up, 2 = right, 3 = down, 4 = left
|
||||
|
||||
// counts the number of times we go forward in time without
|
||||
Int32 numberOfIterationsWithoutNewVisits = 0;
|
||||
|
||||
Int32 previousNumberOfVisitedPositions = 0;
|
||||
|
||||
Int32 numberOfDirectionChanges = 0;
|
||||
|
||||
Boolean guardIsInMapBoundary = true;
|
||||
|
||||
Boolean wasInfiniteLoop = false;
|
||||
|
||||
// Find the initial position and direction of the guard
|
||||
guardLinearPosition = map.IndexOf('^');
|
||||
|
||||
if (guardLinearPosition != -1) // in up direction
|
||||
{
|
||||
guardDirection = 1;
|
||||
// invalid new obstacle position, so return prematurely with
|
||||
// the assumption that it didn't lead to an infinite loop
|
||||
if (newObstacleLinearPosition == guardLinearPosition)
|
||||
return false; // assumed value of wasInfiniteLoop
|
||||
}
|
||||
else // not in up direction
|
||||
{
|
||||
guardLinearPosition = map.IndexOf('>');
|
||||
if (guardLinearPosition != -1) // in right direction
|
||||
guardDirection = 2;
|
||||
else // not in up or right direction
|
||||
{
|
||||
guardLinearPosition = map.IndexOf('v');
|
||||
if (guardLinearPosition != -1) // in down direction
|
||||
guardDirection = 3;
|
||||
else // not in up, right or down direction
|
||||
{
|
||||
guardLinearPosition = map.IndexOf('<');
|
||||
if (guardLinearPosition != -1) // in left direction
|
||||
guardDirection = 4;
|
||||
else // guard not found
|
||||
{
|
||||
guardDirection = -1;
|
||||
guardIsInMapBoundary = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// add intiial guard linear position
|
||||
if (guardIsInMapBoundary) visited.Add(guardLinearPosition);
|
||||
|
||||
while (guardIsInMapBoundary)
|
||||
{
|
||||
// check next position of guard
|
||||
|
||||
// top
|
||||
if (guardDirection == 1)
|
||||
{
|
||||
// if obstacle detected
|
||||
if (guardLinearPosition - (mapWidth + 1) >= 0 &&
|
||||
(
|
||||
map[guardLinearPosition - (mapWidth + 1)] == '#' ||
|
||||
guardLinearPosition - (mapWidth + 1) == newObstacleLinearPosition
|
||||
))
|
||||
{
|
||||
// turn 90 deg clockwise
|
||||
guardDirection = 2;
|
||||
numberOfDirectionChanges++;
|
||||
}
|
||||
// no obstacle detected
|
||||
else
|
||||
// go up one position
|
||||
guardLinearPosition -= mapWidth + 1;
|
||||
}
|
||||
// right
|
||||
else if (guardDirection == 2)
|
||||
{
|
||||
// if obstacle detected
|
||||
if (guardLinearPosition + 1 < map.Length &&
|
||||
(
|
||||
map[guardLinearPosition + 1] == '#' ||
|
||||
guardLinearPosition + 1 == newObstacleLinearPosition
|
||||
))
|
||||
{
|
||||
// turn 90 deg clockwise
|
||||
guardDirection = 3;
|
||||
numberOfDirectionChanges++;
|
||||
}
|
||||
// no obstacle detected
|
||||
else
|
||||
// go up one position
|
||||
guardLinearPosition += 1;
|
||||
}
|
||||
// down
|
||||
else if (guardDirection == 3)
|
||||
{
|
||||
// if obstacle detected
|
||||
if (guardLinearPosition + (mapWidth + 1) < map.Length &&
|
||||
(
|
||||
map[guardLinearPosition + (mapWidth + 1)] == '#' ||
|
||||
guardLinearPosition + (mapWidth + 1) == newObstacleLinearPosition
|
||||
))
|
||||
{
|
||||
// turn 90 deg clockwise
|
||||
guardDirection = 4;
|
||||
numberOfDirectionChanges++;
|
||||
}
|
||||
// no obstacle detected
|
||||
else
|
||||
// go up one position
|
||||
guardLinearPosition += (mapWidth + 1);
|
||||
}
|
||||
// left
|
||||
else if (guardDirection == 4)
|
||||
{
|
||||
// if obstacle detected
|
||||
if (guardLinearPosition - 1 >= 0 &&
|
||||
(
|
||||
map[guardLinearPosition - 1] == '#' ||
|
||||
guardLinearPosition - 1 == newObstacleLinearPosition
|
||||
))
|
||||
{
|
||||
// turn 90 deg clockwise
|
||||
guardDirection = 1;
|
||||
numberOfDirectionChanges++;
|
||||
}
|
||||
// no obstacle detected
|
||||
else
|
||||
// go up one position
|
||||
guardLinearPosition -= 1;
|
||||
}
|
||||
|
||||
// right and left boundary check
|
||||
if (guardLinearPosition > map.Length ||
|
||||
guardLinearPosition < 0 ||
|
||||
map[guardLinearPosition] == '\n')
|
||||
guardIsInMapBoundary = false;
|
||||
|
||||
// top and bottom boundary check
|
||||
if (guardLinearPosition < 0 ||
|
||||
guardLinearPosition >= map.Length)
|
||||
guardIsInMapBoundary = false;
|
||||
|
||||
// if boundary check passes, add position to visited
|
||||
if (guardIsInMapBoundary)
|
||||
{
|
||||
previousNumberOfVisitedPositions = visited.Count;
|
||||
visited.Add(guardLinearPosition);
|
||||
}
|
||||
|
||||
// if there is no change in the number of visited positions
|
||||
if (previousNumberOfVisitedPositions == visited.Count)
|
||||
{
|
||||
numberOfIterationsWithoutNewVisits++;
|
||||
|
||||
// we've followed the whole path again, of which a good approximation is
|
||||
// that the number of unique visited positions plus the number of times
|
||||
// the direction has changes is equal to the number of iterations without new
|
||||
// visits - this will undercount intersections
|
||||
if (numberOfIterationsWithoutNewVisits > (visited.Count + numberOfDirectionChanges))
|
||||
{
|
||||
// Console.WriteLine(" numberOfIterationsWithoutNewVisits = {0:d}", numberOfIterationsWithoutNewVisits);
|
||||
wasInfiniteLoop = true;
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return wasInfiniteLoop;
|
||||
}
|
||||
public Day6()
|
||||
{
|
||||
String fileData = System.IO.File.ReadAllText(@"..\..\..\inputd6.txt");
|
||||
|
||||
|
||||
// set of visited linearPositions
|
||||
HashSet<Int32> visited = [];
|
||||
|
||||
simulateGuardPath(fileData, ref visited);
|
||||
|
||||
Int32 numberOfDistinctPositions = visited.Count;
|
||||
|
||||
Console.WriteLine("numberOfDistinctPositions = {0:d}", numberOfDistinctPositions);
|
||||
|
||||
Int32 numberOfViableNewObstaclePositions = 0;
|
||||
|
||||
Boolean wasInfiniteLoop;
|
||||
|
||||
// a set of unchecked linearPositions
|
||||
HashSet<Int32> uncheckedLinearPositions = [.. visited];
|
||||
|
||||
// a set of alreaedy-checked linearPositions
|
||||
HashSet<Int32> checkedLinearPositions = [];
|
||||
|
||||
Int32 previousUncheckedLinearPositionsCount = uncheckedLinearPositions.Count;
|
||||
|
||||
// while there are unchecked visited positions
|
||||
while (uncheckedLinearPositions.Count > 0)
|
||||
{
|
||||
// clear visited hashset for a fresh start per iteration
|
||||
visited.Clear();
|
||||
|
||||
// get first non-checked linear position
|
||||
var firstNonCheckedLinearPosition = uncheckedLinearPositions.First();
|
||||
|
||||
wasInfiniteLoop = simulateGuardPath(fileData, ref visited, firstNonCheckedLinearPosition);
|
||||
|
||||
// if the guard is in a loop, we have a viable obstacle position
|
||||
if (wasInfiniteLoop)
|
||||
numberOfViableNewObstaclePositions++;
|
||||
|
||||
// update checkedLinearPositions
|
||||
checkedLinearPositions.Add(firstNonCheckedLinearPosition);
|
||||
|
||||
// remove already-checked linear positions from visited
|
||||
// so it only has new positions to add to our uncheckedLinearPositions
|
||||
visited.ExceptWith(checkedLinearPositions);
|
||||
|
||||
previousUncheckedLinearPositionsCount = uncheckedLinearPositions.Count;
|
||||
|
||||
// update uncheckedLinearPositions to remove firstNonCheckedLinearPosition
|
||||
// and add newly visisted linear positions
|
||||
uncheckedLinearPositions.Remove(firstNonCheckedLinearPosition);
|
||||
uncheckedLinearPositions.UnionWith(visited);
|
||||
|
||||
// if (uncheckedLinearPositions.Count > previousUncheckedLinearPositionsCount)
|
||||
// Console.WriteLine("(change) uncheckedLinearPositions.Count = {0:d}", uncheckedLinearPositions.Count - previousUncheckedLinearPositionsCount);
|
||||
}
|
||||
|
||||
Console.WriteLine("numberOfViableNewObstaclePositions = {0:d}", numberOfViableNewObstaclePositions);
|
||||
|
||||
// to keep the console window from closing
|
||||
Console.ReadKey();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -11,7 +11,8 @@ namespace Advent24
|
|||
//_ = new Day2();
|
||||
//_ = new Day3();
|
||||
//_ = new Day4();
|
||||
_ = new Day5();
|
||||
// _ = new Day5();
|
||||
_ = new Day6();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -0,0 +1,130 @@
|
|||
..........#...........#...........#.............................#......................#.........#................................
|
||||
..........................#.........#......#.................................#...........................#........................
|
||||
..................................#...#................................................................................#..........
|
||||
.#...............#.....#..........#.........#......#........#................................#......#.............................
|
||||
...#.......#.............#.............................................#.........##...............#.................#.............
|
||||
.......................................#.............#..................#........#.......#.........#...............#.........#....
|
||||
.....#..................#..#..#.........................#...................#....#........#.............................#.........
|
||||
.......#.............................#..........#......#..........................##......#.......................##..............
|
||||
.....#.....#........................................................................................#.......#.....................
|
||||
.................................#............#...#.....................................................#.........#...............
|
||||
...............#.....#..#....#....#.....................................................#............#........#.#.................
|
||||
.......#.....#...........................................................#............................#.................#....#....
|
||||
...........................#.................#....................................#...............#..#........................#...
|
||||
.....#.........................................#.................#...##....................................#......................
|
||||
.............#...#..................#......#.................#..........................................#.....#..........#........
|
||||
.................#...............#............#.......#.#...............................................#..................#......
|
||||
.....#..#.....................#.......................................................#..............#..............#.......##....
|
||||
..##........#....................................................#.............#..............#........................#..#.......
|
||||
..............................#...........#...#........................#............#..........................#........#........#
|
||||
.....................................##...............................#............#............#....#............................
|
||||
...##........................#.....#....#.........#.................................................#.............................
|
||||
...............................#................................#...............#.....#.....................#.....................
|
||||
................................................#..........#....#............................#.....#.......#..................#...
|
||||
.............#.....#.........#.#....#................##......#.............#......................................................
|
||||
..........#..............#..........#......#.........#...#.........................................#.#.....#.........#............
|
||||
..................#......................#.............................#...................#.....................................#
|
||||
................#.....#..............................#.............#.............#..#.....#....................................#..
|
||||
.........#.#................#.........#.................#...................#................................#................#...
|
||||
.............................................................#..............#.....................................................
|
||||
......#.........................#...........#.........#..................#....................................#..#...........##...
|
||||
.............................................................................#.............#........................#...#.........
|
||||
......#......#..#............#..............................................#....#..#..#................#.........#....#..........
|
||||
........#........#.........#....................................................^..#...#....................#...............#.....
|
||||
..#....#...#.......................................................................................................#..............
|
||||
.....#...........................................#..............#.........#....#........................................#.........
|
||||
.....................................#..............#............................................................#................
|
||||
.....#.......................#........................#..........#.............#.................#..................#.............
|
||||
.......................................#......#.....................................#.........................#...................
|
||||
...........................................................................................#............................##........
|
||||
..#............#..........................#...........#...#..................#......#.................#.#.................#......#
|
||||
.###......#....................#...#...........................................................#.........#.....#..............#.#.
|
||||
....................................#..........#.....#.......................#...............#.....#......#...................#...
|
||||
...#......#..................#......#.......#..............#..............#.......................................................
|
||||
..........#....................................................................#................##.#...#..........................
|
||||
.........................................................#..................##.....................#..##..........................
|
||||
..................#......#.................................#.................#.##................................................#
|
||||
...#..........#...#..#..............................................#...........................##........#.......................
|
||||
.....#................................................#...........#..................#...#.................................#......
|
||||
.......#.....#.........................#..........................................................................................
|
||||
....................................................#........#....#....................................##..............#.....#....
|
||||
............#........#.........................#.................................#..........................................#...#.
|
||||
.....................................#........................#...................#......#.#...........#..#..........#...........#
|
||||
................#...............#.........................#.........................#........#..#.................................
|
||||
.............#.........#.............#.#.#.........#...................#.......#.......................#..........................
|
||||
.............#......................................................#................................................#.......#....
|
||||
....#....................................................................#.#........#.................#..........................#
|
||||
.................................#......#....................................................................#.....#..............
|
||||
............##...................#.......................................................................#.........#........#.....
|
||||
#..................................................#..#...............#............#.............#...............................#
|
||||
.............................#.................................#.....#..........................#.............#..#...#...#........
|
||||
...#.....#..............................#.#......................................#................................................
|
||||
...#............##...............................#............#..............................#................................#...
|
||||
#.................#......##..............................................................#...........#........#...#...............
|
||||
....##.....................................................................................................#.#....................
|
||||
#.................#..................................................#..................................................#.........
|
||||
.........#.........#...........................#.................#.#.............................#................................
|
||||
................................#............#................................................................#...................
|
||||
.....................................#............................................#.##......##........#...........................
|
||||
....#....................................................#...#.#.#....................................................#...........
|
||||
.........................#.#...................#...................##...............#........................#....................
|
||||
..................................#...................................................................#.......#..................#
|
||||
...................#.............................................#.......................#.#.....................#....#...........
|
||||
#....................................#.#..#.#..........#.........#.........##.........#......................#............#.......
|
||||
...............................................................#.............................##....#.......#......................
|
||||
.............#......#.#.........#............................#............................#.......................................
|
||||
......................#.........#.........................................................#...#............#......................
|
||||
...................#.....#.....................................................#.....................................#............
|
||||
...............................#.....#..................#.......##................................................................
|
||||
.............................................#.........................#...........#..............................#..#............
|
||||
#..##..................................................................................................#......#...........#.....#.
|
||||
.......................................................#.....................#.............................#......................
|
||||
...........................................................................................................#......................
|
||||
......................#..............................................................#............................................
|
||||
...........................#.....#......................................#.........#........#..#.#.................................
|
||||
.#.......#........................................................................................................................
|
||||
.#.......#...........................................#................................#...........................................
|
||||
.........................................................#........................................#......#........................
|
||||
...............................#...#........#............................................#.................#......................
|
||||
......#.........................#......................#.....#.#..............#..................#.......#..................#.....
|
||||
.................#........#...#........................#.............................#............................................
|
||||
#...........................................................................#............................#................#.......
|
||||
..........................................................................#................#......................................
|
||||
.............#.............................................................................#.........................#............
|
||||
.#...........#.......#.......#.....#....#.......#........#....................#........................#........................#.
|
||||
...#..............#.............................#.............................................................#...#..#..........#.
|
||||
......#......#.#...............##................................................................................................#
|
||||
....#........#.##......#...#......................................................................................................
|
||||
..#..#.#.#.....................#................................#...................................#.....#...#...................
|
||||
.....................#.#........#..............##..............#.................#..............................................#.
|
||||
...................................................................................#........#.......#....#............#...........
|
||||
.....#....#..................#...............#.............................................#.#....................#...............
|
||||
.....................#..........#............#..................................#......................#.#.....#................#.
|
||||
..........#.........................................#...............#.............................................................
|
||||
.......#......................#.............#.....#..............#........................#.....#.........#.................#...#.
|
||||
..................................................................#.....#...............................................#........#
|
||||
.......#..........#.......#....#.......#..........#....#............................................#.#...........................
|
||||
..#...........#..............................#....................#....................#...#......................................
|
||||
.......#...............................#............#.....#.....................#.................................................
|
||||
.........#..................#..................#..................................................................................
|
||||
..........................................................................................#....#...................#.......##.....
|
||||
..................#.............................##.......................................................#.......#......#......#..
|
||||
...#.......#..............................................................................................#.......................
|
||||
............#..#..............................................................#...........##....#....#.#................#........#
|
||||
............#.........................#........#....#..#..................................#..................#....................
|
||||
......##......................#...##..............................#...............................................................
|
||||
........................#................#..............#...##...............................#..................##....#...........
|
||||
....#.#...#.....#..................................#..............................#...........#.....................#.............
|
||||
......................#.........................................................................#..........#.............#........
|
||||
.#......#............................................................#...............................#...#........................
|
||||
.......##.....................#.....#...........#......##.......##...................#...............................#............
|
||||
...#...#........#...............#......#......#.....#...#.................................................................#.......
|
||||
..................#.......................#...............................................#.................#.............#..#....
|
||||
.....................#.......#....#...#............................#.....................#............#.....................#.....
|
||||
................................................................#....#......#............#..................#.........#...........
|
||||
.......................#...................#..............................................................................###.....
|
||||
...............................#...........#................................#........#..#....#............................#.......
|
||||
....#......#...............................#...............#......................................#...............................
|
||||
...........#...........................##.........................................................................#.#.............
|
||||
.........................#.........#.........................................#.....#...................#.....#.......#............
|
||||
.............................#.....#................##..#.....................#...................................................
|
||||
Loading…
Reference in New Issue