@@ -1,25 +1,248 @@
using System ;
using System.Collections.Generic ;
using System.Diagnostics ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace AdventOfCode.Problems.AOC2024.Day9 ;
//[ProblemInfo(2024, 9, "Disk Fragmenter")]
internal class : Problem
[ProblemInfo(2024, 9, " Disk Fragmenter")]
internal class DiskFragmenter : Problem < long , long >
{
private int [ ] _data = [ ] ;
public override void CalculatePart1 ( )
{
throw new NotImplementedException ( ) ;
var data = Expand ( _data ) ;
Compact ( data ) ;
Part1 = ComputeHash ( data ) ;
}
public override void CalculatePart2 ( )
{
throw new NotImplementedException ( ) ;
var blocks = ExpandBlocks ( _data ) ;
CompactV2 ( blocks ) ;
//Print(blocks);
// Too High: 8838426222802
Part2 = ComputeHashV2 ( blocks ) ;
}
public static void Print ( List < Block > blocks , int idx = - 1 )
{
for ( int i = 0 ; i < blocks . Count ; i + + )
{
Console . ResetColor ( ) ;
if ( i = = idx )
Console . BackgroundColor = ConsoleColor . Green ;
if ( blocks [ i ] . isEmpty )
Console . ForegroundColor = ConsoleColor . DarkGray ;
Console . Write ( blocks [ i ] . ToString ( ) ) ;
}
Console . ResetColor ( ) ;
Console . WriteLine ( ) ;
}
public static void Print ( int [ ] data )
{
Console . WriteLine ( data . Select ( x = > x = = - 1 ? " " : x . ToString ( ) ) . AsJoinedString ( "" ) . Trim ( ) ) ;
}
public static int [ ] Expand ( int [ ] data )
{
var result = new List < int > ( data . Sum ( ) ) ;
var isFile = true ;
var id = 0 ;
foreach ( var item in data )
{
if ( isFile )
result . AddRange ( Enumerable . Repeat ( id + + , item ) ) ;
else
result . AddRange ( Enumerable . Repeat ( - 1 , item ) ) ;
isFile = ! isFile ;
}
return [ . . result ] ;
}
public static void Compact ( int [ ] data )
{
var readPos = data . Length - 1 ;
var writePos = 0 ;
var curValue = 0 ;
var isWriting = false ;
while ( true )
{
if ( readPos - 2 < writePos & & ! isWriting )
break ;
if ( isWriting )
{
while ( writePos < data . Length )
{
if ( data [ writePos ] = = - 1 )
{
data [ writePos ] = curValue ;
data [ readPos ] = - 1 ;
curValue = - 1 ;
writePos + + ;
break ;
}
writePos + + ;
}
isWriting = false ;
}
else
{
do
{
curValue = data [ readPos ] ;
if ( curValue ! = - 1 )
{
isWriting = true ;
break ;
}
readPos - - ;
}
while ( readPos > = 0 ) ;
}
}
}
public static long ComputeHash ( int [ ] data )
{
long hash = 0 ;
//Compensate to incomplete compaction
long idx = 0 ;
for ( long i = 0 ; i < data . Length ; i + + )
{
if ( data [ i ] = = - 1 )
continue ;
hash + = ( idx + + ) * ( long ) data [ i ] ;
}
return hash ;
}
public static List < Block > ExpandBlocks ( int [ ] data )
{
var blocks = new List < Block > ( ) ;
var isFile = true ;
var id = 0 ;
foreach ( var block in data )
{
if ( block = = 0 )
{
isFile = ! isFile ;
continue ;
}
if ( isFile )
blocks . Add ( new Block ( id + + , block ) ) ;
else
blocks . Add ( new Block ( block ) ) ;
isFile = ! isFile ;
}
return blocks ;
}
public static void CompactV2 ( List < Block > blocks )
{
for ( int idx = blocks . Count - 1 ; idx > = 0 ; idx - - )
{
var block = blocks [ idx ] ;
if ( block . isEmpty )
continue ;
var emptyPos = FindFirstEmptyBlock ( block . length , idx , blocks ) ;
if ( emptyPos = = - 1 )
continue ;
var emptyBlock = blocks [ emptyPos ] ;
//Replace Empty Block
if ( emptyBlock . length = = block . length )
blocks [ emptyPos ] = block ;
else
{
//Insert and Shrink Empty Block
blocks . Insert ( emptyPos , block ) ;
idx + = 1 ;
emptyBlock . length - = block . length ;
}
//Merge Left and Right empty blocks
if ( idx + 1 < blocks . Count & & blocks [ idx + 1 ] . isEmpty & & idx - 1 > 0 & & blocks [ idx - 1 ] . isEmpty )
{
blocks [ idx - 1 ] . length + = block . length + blocks [ idx + 1 ] . length ;
blocks . RemoveAt ( idx ) ;
blocks . RemoveAt ( idx ) ;
idx - = 1 ;
}
//Extend Right Block
else if ( idx + 1 < blocks . Count & & blocks [ idx + 1 ] . isEmpty )
blocks [ idx + 1 ] . length + = block . length ;
//Extend Left Block
else if ( idx - 1 > 0 & & blocks [ idx - 1 ] . isEmpty )
blocks [ idx - 1 ] . length + = block . length ;
//Insert new Empty Block
else
blocks [ idx ] = new Block ( block . length ) ;
//Print(blocks, idx);
}
static int FindFirstEmptyBlock ( int length , int limit , List < Block > blocks )
{
for ( int i = 0 ; i < limit ; i + + )
{
var block = blocks [ i ] ;
if ( block . isEmpty & & block . length > = length )
return i ;
}
return - 1 ;
}
}
public static long ComputeHashV2 ( List < Block > blocks )
{
long hash = 0 ;
long pos = 0 ;
for ( int i = 0 ; i < blocks . Count ; i + + )
{
var block = blocks [ i ] ;
if ( ! block . isEmpty )
{
//There's probably an equation for this
for ( int x = 0 ; x < block . length ; x + + )
{
hash + = block . id * pos + + ;
}
} else
pos + = block . length ;
}
return hash ;
}
public override void LoadInput ( )
{
throw new NotImplementedException ( ) ;
_data = ReadInputText ( "input.txt" ) . Select ( x = > ( int ) ( x - '0' ) ) . ToArray ( ) ;
}
}
public class Block
{
public bool isEmpty ;
public int id ;
public int length ;
public Block ( int id , int length )
{
this . id = id ;
this . length = length ;
}
public Block ( int length )
{
isEmpty = true ;
this . length = length ;
}
public override string ToString ( )
{
return isEmpty ? $"[{length}]" : $"{id}:{length}" ;
}
}
