Day 5

2023/day5/p1.rb

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+# frozen_string_literal: true
+
+f = File.open('./2023/day5/data')
+seeds = f.first.strip.split(': ')[1].split(' ').map(&:to_i)
+updated_seeds = seeds.clone
+
+f.each_line do |line|
+  seeds = updated_seeds if line.include? 'map'
+  next if line.include?('seed') || line.strip.empty? || line.include?('map')
+
+  source_start = line.split(' ')[1].to_i
+  dest_start = line.split(' ')[0].to_i
+  range = line.split(' ')[2].to_i
+
+  updated_seeds = seeds.each_with_index.map do |seed, i|
+    if seed >= source_start && seed < source_start + range
+      dest_start + (seed - source_start)
+    else
+      updated_seeds[i]
+    end
+  end
+end
+
+puts updated_seeds.min

2023/day5/p2.rb

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+# frozen_string_literal: true
+
+# @brief Maps a range from one range to another
+def map_range(source, map_to_range)
+  offset = source.first - map_to_range[:source_range].first
+  range = source.last - source.first
+  (map_to_range[:dest_range].first + offset)..(map_to_range[:dest_range].first + offset + range)
+end
+
+# @brief Augments a list of ranges to include all values between the first and last range
+def augment_ranges(ranges, min_val, max_val)
+  augmented_ranges = []
+  ranges.sort_by! { |range| range[:source_range].first }
+
+  # Add the first range if it doesn't start at min_val
+  if ranges[0][:source_range].first > min_val
+    augmented_ranges << {
+      source_range: (min_val..(ranges[0][:source_range].first - 1)),
+      dest_range: (min_val..(ranges[0][:source_range].first - 1))
+    }
+  end
+
+  # Add all ranges between the ranges that are in the list and the ones already in the list
+  ranges.each do |range|
+    # Add the range that goes from the previous to the current range
+    if !augmented_ranges.empty? && (range[:source_range].first > augmented_ranges[-1][:source_range].last + 1)
+      augmented_ranges << {
+        source_range: ((augmented_ranges[-1][:source_range].last + 1)..(range[:source_range].first - 1)),
+        dest_range: ((augmented_ranges[-1][:source_range].last + 1)..(range[:source_range].first - 1))
+      }
+    end
+    augmented_ranges << range
+  end
+
+  # Add the last range if it doesn't end at max_val
+  if ranges[-1][:source_range].last < max_val
+    augmented_ranges << {
+      source_range: ((ranges[-1][:source_range].last + 1)..max_val),
+      dest_range: ((ranges[-1][:source_range].last + 1)..max_val)
+    }
+  end
+  augmented_ranges
+end
+
+# Start of main program
+f = File.open('./2023/day5/data')
+seeds_in = f.first.strip.split(': ')[1].split(' ').map(&:to_i)
+seeds = []
+
+# Convert the seeds into ranges
+i = seeds_in.length - 1
+while i.positive?
+  seeds << (seeds_in[i - 1]..(seeds_in[i - 1] + seeds_in[i]))
+  i -= 2
+end
+seeds.sort_by!(&:first)
+
+ranges = []
+f.each_line do |line|
+  next if line.include?('seed') || line.strip.empty?
+
+  # Map indicates end of previous given mapping, map all seeds to new ranges
+  if line.include?('map') || f.eof?
+    puts line
+    new_seeds = []
+    seeds.each do |seed_range|
+      last_pos = seed_range.first
+      ranges = augment_ranges ranges, seeds[0].first, seeds[-1].last
+      ranges.each do |range|
+        next if seed_range.first > range[:source_range].last || seed_range.last < range[:source_range].first
+
+        pos = [seed_range.last, range[:source_range].last].min
+        new_seeds << map_range((last_pos..pos), range)
+        puts "Mapped #{last_pos..pos} to #{map_range((last_pos..pos), range)}"
+        last_pos = pos + 1
+      end
+    end
+    ranges = []
+    seeds = new_seeds
+    next
+  end
+
+  source_start = line.split(' ')[1].to_i
+  dest_start = line.split(' ')[0].to_i
+  range = line.split(' ')[2].to_i
+  ranges << {
+    source_range: (source_start..(source_start + range - 1)),
+    dest_range: (dest_start..(dest_start + range - 1))
+  }
+end
+
+seeds.sort_by!(&:first)
+puts seeds[0].first