Very Simple Triangles

Question

Write a program or function that takes in a positive integer (via stdin, command line, or function arg) and prints or returns a string of that many of these small triangles tiled together, alternating which way they point:

 /\
/__\

This sole triangle is the output if the input is 1.

If the input is 2, the output is

  ____
 /\  /
/__\/

If the input is 3, the output is

  ____
 /\  /\
/__\/__\

If the input is 4, the output is

  ________
 /\  /\  /
/__\/__\/

And so on. Your program must support inputs up to 2¹⁶ - 1 = 65535.

Details

• The leftmost triangle always points upwards.
• There may be trailing spaces but there may not be unnecessary leading spaces.
• There may be an optional trailing newline.
• Note that for 1 the output is two lines long but otherwise it's three. This is required.
• The shortest submission in bytes wins.

Answer 1

C# (.NET Core), 151 bytes

Without LINQ - 3 string array.

Like most of these, this fails if the integer goes over the max char count per line for stdout.

p=>{var s=new string[3]{ "  ","",""};for(var j=0;j< p;){if(j++%2<1){s[1]+=j==p-1?@" /":@" /\ ";s[2]+=j==p-1?@"/":@"/__\";}else s[0]+="____";}return s;}

Try it online!

Answer 2

Retina, 88 bytes

K`  ____¶ /\  /¶/__\/
%`....$
$+*$&
%`(.+)\1$
$1
(  (____)*)__(¶.*)  /(¶.*)/
$1$3$4
G`\S

Try it online! Explanation:

K`  ____¶ /\  /¶/__\/

Replace the input with a pair of triangles.

%`....$
$+*$&

Multiply the triangles by the original input.

%`(.+)\1$
$1

Divide the triangles by 2.

(  (____)*)__(¶.*)  /(¶.*)/
$1$3$4

Remove the left-over half triangle.

G`\S

Remove the first line if it is now blank.