CJam、148の 116 109バイト
これには予想よりもかなり時間がかかりました。もともと、ダイヤモンドチャレンジのように左上の象限を繰り返し構築し、残りをミラーリングから取得したかっただけです。しかし、アンダースコアが上半分と下半分の間の鏡面対称性に従わないことに気づきませんでした。そのため、右半分を繰り返し生成し、1回だけ（左に）ミラーリングするために、そのほとんどをやり直す必要がありました。
S]2[l~]:(f#:+2bW%{_,2/~:T;{IT):T1<'\'/?S?S++}%__,2/=,2/I'_S?*_S+a@+\I'/S?S++a+}fI{)T)2*2$,-*1$W%"\/"_W%er@N}/
ここでテストしてください。
フィボナッチ風の例：
8 3 1 5 2
________________
/ \
/ \
/ __________ \
/ / \ \
/ / ______ \ \
/ / / ____ \ \ \
/ / / / __ \ \ \ \
/ / / / / \ \ \ \ \
\ \ \ \ \__/ / / / /
\ \ \ \____/ / / /
\ \ \______/ / /
\ \ / /
\ \__________/ /
\ /
\ /
\________________/
説明：
上で述べたように、右半分を繰り返し構築することから始めます。つまり、最初はグリッド内に1つのスペースしかありません。次に、可能なリングごとに、既存のグリッドをスペースで囲むか、新しい半六角形のいずれかを囲みます。
それが完了したら、各行を左にミラーリングし、正しい位置合わせのために先頭にスペースを埋め込みます。コードの内訳は次のとおりです。
"Prepare the input and the grid:";
S]2[l~]:(f#:+2bW%
S] "Push string with a space and wrap it in an array. This is the grid.";
2 "Push a 2 for future use.";
[l~] "Read and evaluate the input, wrap it in an array.";
:( "Decrement each number by 1.";
f# "Map each number i to 2^i.";
:+ "Sum them all up.";
2b "Get the base two representation.";
W% "Reverse the array.":
"At this point, the stack has the proto-grid at the bottom, and an array of 1s and
0s on top, which indicates for each hexagon if it's present or not.";
"Next is a for loop, which runs the block for each of those 0s and 1s, storing the
actual value in I. This block adds the next semi-hexagon or spaces.";
{ ... }fI
"First, append two characters to all existing lines:";
_,2/~:T;{IT):T1<'\'/?S?S++}%
_ "Duplicate the previous grid.";
,2/ "Get its length, integer-divide by 2.";
~:T; "Get the bitwise complement and store it in T. Discard it.";
{ }% "Map this block onto each line of the grid.";
I "Push the current hexagon flag for future use.";
T):T "Push T, increment, store the new value.";
1<'\'/? "If T is less than 1, push \, else push /.";
S? "If the current flag is 0, replace by a space.";
S++ "Append a space and add it to the current line.";
"So for hexagons this appends '\ ' to the top half and '/ ' to the bottom half.
For empty rings, it appends ' ' to all lines.";
"Now add a new line to the top and the bottom:"
__,2/=,2/I'_S?*_S+a@+\I'/S?S++a+
__ "Get two copies of the grid.";
,2/ "Get its length, integer-divide by 2.";
= "Get that line - this is always the middle line.";
,2/ "Get ITS length, integer'divide by 2.";
I'_S?* "Get a string of that many _ or spaces depending on the
current flag.";
_S+ "Duplicate and a space.";
a@+ "Wrap in an array, pull up the grid, and prepend the line.";
\ "Swap with the other copy.";
I'/S? "Choose between / and a space depending on the flag.";
S++ "Append a space, and add both characters to the line.";
a+ "Wrap in an array, and append line to the grid.";
"This is all. Rinse and repeat for all rings. The result will look something like this:
_____
\
___ \
__ \ \
_ \ \ \
\ \ \ \
_/ / / /
__/ / /
___/ /
/
_____/
Note that there are still trailing spaces.";
"Finish up all lines. These will not be joined together any more, but simply left
on the stack in pieces to printed out back-to-back at the end of the program.
The following runs the given block for each line:";
{ ... } /
"This generates the necessary indentation, then mirrors the lines and puts them
in the right order:"
)T)2*2$,-*\_W%"\/"_W%er\N
) "Slice off that trailing space, but leave it on the stack.";
T "Remember T? That still has something like the the size of
the grid from the last iteration. In fact it's N-1, where
N is the largest visible hexagon. We can use that to figure
out how many spaces we need.";
)2* "Increment and double.";
2$ "Copy the current line.";
,- "Subtract its length from 2*N.";
* "Repeat the space that often. This is our indentation.";
\_ "Swap with the line and duplicate.";
W% "Reverse the line.";
"\/"_W%er "Replace slashes with backslashes and vice versa.";
\ "Swap with the original line.";
N "Push a line break.";
1最も内側または最も外側の六角形を指しますか？