Data commit

Task/Mutual-recursion/Eiffel/mutual-recursion.e

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+class
+	APPLICATION
+
+create
+	make
+
+feature
+
+	make
+			-- Test of the mutually recursive functions Female and Male.
+		do
+			across
+				0 |..| 19 as c
+			loop
+				io.put_string (Female (c.item).out + " ")
+			end
+			io.new_line
+			across
+				0 |..| 19 as c
+			loop
+				io.put_string (Male (c.item).out + " ")
+			end
+		end
+
+	Female (n: INTEGER): INTEGER
+			-- Female sequence of the Hofstadter Female and Male sequences.
+		require
+			n_not_negative: n >= 0
+		do
+			Result := 1
+			if n /= 0 then
+				Result := n - Male (Female (n - 1))
+			end
+		end
+
+	Male (n: INTEGER): INTEGER
+			-- Male sequence of the Hofstadter Female and Male sequences.
+		require
+			n_not_negative: n >= 0
+		do
+			Result := 0
+			if n /= 0 then
+				Result := n - Female (Male (n - 1))
+			end
+		end
+
+end