A-M baby

Task/Generator-Exponential/Ruby/generator-exponential-1.rb

@@ -0,0 +1,21 @@
+# This solution cheats and uses only one generator!
+
+def powers(m)
+  return enum_for(:powers, m) unless block_given?
+
+  n = 0
+  loop { yield n ** m; n += 1 }
+end
+
+def squares_without_cubes
+  return enum_for(:squares_without_cubes) unless block_given?
+
+  cubes = powers(3)
+  c = cubes.next
+  powers(2) do |s|
+    (c = cubes.next) until c >= s
+    yield s unless c == s
+  end
+end
+
+p squares_without_cubes.take(30).drop(20)

Task/Generator-Exponential/Ruby/generator-exponential-2.rb

@@ -0,0 +1,25 @@
+# This solution uses three generators.
+
+def powers(m)
+  return enum_for(:powers, m) unless block_given?
+
+  n = 0
+  loop { yield n ** m; n += 1 }
+end
+
+def squares_without_cubes
+  return enum_for(:squares_without_cubes) unless block_given?
+
+  cubes = powers(3)
+  c = cubes.next
+  squares = powers(2)
+  loop do
+    s = squares.next
+    (c = cubes.next) until c >= s
+    yield s unless c == s
+  end
+end
+
+answer = squares_without_cubes
+20.times { answer.next }
+p (1..10).map { answer.next }