June 2018 Update

Task/Binary-search/N-t-roff/binary-search.n

@@ -0,0 +1,38 @@
+.de end
+..
+.de array
+.	nr \\$1.c 0 1
+.	de \\$1.push end
+.		nr \\$1..\\\\n+[\\$1.c] \\\\$1
+.	end
+.	de \\$1.pushln end
+.		if \\\\n(.$>0 .\\$1.push \\\\$1
+.		if \\\\n(.$>1 \{ \
+.			shift
+.			\\$1.pushln \\\\$@
+\}
+.	end
+..
+.
+.de binarysearch
+.	nr min 1
+.	nr max \\n[\\$1.c]
+.	nr guess \\n[min]+\\n[max]/2
+.	while !\\n[\\$1..\\n[guess]]=\\$2 \{ \
+.		ie \\n[\\$1..\\n[guess]]<\\$2 .nr min \\n[guess]+1
+.		el .nr max \\n[guess]-1
+.
+.		if \\n[min]>\\n[max] \{
+.			nr guess 0
+.			break
+.		\}
+.		nr guess \\n[min]+\\n[max]/2
+.	\}
+\\n[guess]
+..
+.array a
+.a.pushln 1 4 9 16 25 36 49 64 81 100 121 144
+.binarysearch a 100
+.br
+.ie \n[guess]=0 The item \fBdoesn't exist\fP.
+.el The item \fBdoes exist\fP.