new tasks

Task/Forest_fire/Ruby/forest_fire.rb

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+require 'enumerator'
+
+def transition arr, tree_prob, fire_prob
+  arr.enum_with_index.map do |cell, i|
+    if i == 0 or i == arr.length - 1
+      # boundary conditions: cells are always empty here
+      :empty
+    else
+      case cell
+      when :fire
+        # burning cells become empty
+        :empty
+      when :empty
+        # empty cells grow a tree with probability tree_prob
+        rand < tree_prob ? :tree : :empty
+      when :tree
+        # check my neighbouring cells, are they on fire?
+        if arr[i - 1] == :fire or arr[i + 1] == :fire
+          :fire
+        else
+          # neighbours not on fire, but catch fire at random
+          rand < fire_prob ? :fire : :tree
+        end
+      end
+    end
+  end
+end
+
+def pretty_print arr
+  # colour the trees green, the fires red, and the empty spaces black
+  print(arr.map { |cell|
+    "\e[3" +
+      case cell
+      when :tree
+        "2mT"
+      when :fire
+        "1mF"
+      when :empty
+        "0m "
+      end + "\e[0m"
+  }.join)
+end
+
+N = 20    # 20 trees
+P = 0.5   # probability of growing a tree
+F = 0.1   # probability of catching on fire
+
+srand Time.now.to_i
+
+# each cell has a 50/50 chance of being a tree
+array = (1..N).map { rand < 0.5 ? :tree : :empty }
+array[0] = array[-1] = :empty  # boundary conditions
+pretty_print array
+puts
+
+begin
+  array = transition(array, P, F)
+
+  pretty_print array
+end while gets.chomp.downcase != "q"