「🎉」 init(2025): day 1

2024/day10/part2.rb

@@ -0,0 +1,54 @@
+require 'set'
+
+def find_trailheads(grid)
+  trailheads = []
+  grid.each_with_index do |row, y|
+    row.each_char.with_index do |height, x|
+      trailheads << [x, y] if height == '0'
+    end
+  end
+  trailheads
+end
+
+def find_path(grid, x, y, visited)
+  score = 0
+
+  return 1 if grid[y][x] == '9'
+
+  visited.add([x, y])
+
+  [[-1, 0], [1, 0], [0, -1], [0, 1]].each do |x_dir, y_dir|
+    nx, ny = x + x_dir, y + y_dir
+    next unless ny.between?(0, grid.size - 1) && nx.between?(0, grid[0].length - 1)
+    next if visited.include?([nx, ny])
+    
+    if grid[ny][nx].to_i == grid[y][x].to_i + 1
+      score += find_path(grid, nx, ny, visited)
+    end
+  end
+
+  visited.delete([x, y])
+  score
+end
+
+
+
+if File.exists?("input.txt")
+  file = File.open("input.txt")
+  file_data = file.read
+  file.close
+else
+  file_data = "89010123\n78121874\n87430965\n96549874\n45678903\n32019012\n01329801\n10456732"
+end
+
+grid = file_data.split("\n")
+
+trailheads = find_trailheads(grid)
+result = 0
+
+trailheads.each do |trailhead|
+  result += find_path(grid, trailhead[0], trailhead[1], Set.new)
+  #puts result
+end
+
+puts "result : #{result}"