day 15 part 2 solution

Author: baton

15/2.cpp

@@ -0,0 +1,113 @@
+#include <iostream>
+#include <fstream>
+#include <iterator>
+#include <memory>
+#include <vector>
+#include <string>
+#include <set>
+#include <map>
+#include <algorithm>
+
+
+using field_t = std::vector< std::vector< uint64_t > >;
+using point_t = std::pair< uint64_t, uint64_t >;
+using visited_t = std::map< point_t, uint64_t >;
+using front_t = std::set< point_t >;
+
+
+inline bool in_visited( point_t const & p, visited_t const & visited )
+{
+	return visited.find( p ) != visited.end();
+}
+
+inline visited_t nexts( uint64_t const x, uint64_t const y, field_t const & field )
+{
+	visited_t n;
+
+	if( x != 0 )
+		n.emplace( std::make_pair( x - 1, y ), field[ x - 1 ][ y ] );
+	if( y != 0 )
+		n.emplace( std::make_pair( x, y - 1 ), field[ x ][ y - 1 ] );
+	if( x != field.size() - 1 )
+		n.emplace( std::make_pair( x + 1, y ), field[ x + 1 ][ y ] );
+	if( y != field[ 0 ].size() - 1 )
+		n.emplace( std::make_pair( x, y + 1 ), field[ x ][ y + 1 ] );
+
+	return n;
+}
+
+inline visited_t nexts( point_t const & p, field_t const & field )
+{
+	return nexts( p.first, p.second, field );
+}
+
+inline uint64_t incl( uint64_t x )
+{
+	++x;
+	if( x == 10 )
+		x = 1;
+	return x;
+}
+
+
+int main( int argc, char * argv[] )
+{
+	if( argc < 2 )
+		return 0;
+
+	field_t field;
+
+	std::ifstream ifs( argv[ 1 ] );
+	for( std::string s; std::getline( ifs, s ); )
+	{
+		std::vector< uint64_t > v;
+		std::transform(
+			s.begin(), s.end(),
+			std::back_inserter< std::vector< uint64_t > >( v ),
+			[]( char const c ) -> uint64_t
+			{
+				return c - '0';
+			}
+		);
+		size_t const sz( v.size() );
+		for( size_t i( 1 ); i != 5; ++i )
+			for( size_t j( 0 ); j != sz; ++j )
+				v.push_back( incl( v[ sz * ( i - 1 ) + j ] ) );
+
+		field.push_back( std::move( v ) );
+	}
+
+	size_t const sz( field.size() );
+	for( size_t i( 1 ); i != 5; ++i )
+		for( size_t j( 0 ); j != sz; ++j )
+		{
+			std::vector v( field[ sz * ( i - 1 ) + j ] );
+			std::for_each( v.begin(), v.end(), []( uint64_t & x ) { x = incl( x ); } );
+			field.push_back( std::move( v ) );
+		}
+
+	point_t const target{ field.size() - 1, field[ 0 ].size() - 1 };
+
+	visited_t weights;
+	weights.emplace( std::make_pair( 0, 0 ), 0 );
+
+	front_t front;
+	front.emplace( std::make_pair( 0, 0 ) );
+
+	while( !front.empty() )
+	{
+		point_t const point( front.extract( front.begin() ).value() );
+		for( auto const & [ p, w ] : nexts( point, field ) )
+		{
+			if( !in_visited( p, weights ) || ( weights[ point ] + w < weights[ p ] ) )
+			{
+				weights[ p ] = weights[ point ] + w;
+				front.emplace( p );
+			}
+		}
+	}
+
+	std::cout << "result = " << weights[ target ] << std::endl;
+
+	return 0;
+}