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Pascal's triangle: Difference between revisions
added two variants
(Emacs Lisp -- Pascal's triangle) |
(added two variants) |
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=={{header|Emacs Lisp}}==
===Using mapcar and append, returing a list of rows===
<lang lisp>(defun next-row (row)
(mapcar* #'+ (cons 0 row)
Line 1,912 ⟶ 1,913:
(1 4 6 4 1)
(1 5 10 10 5 1))
</pre>
===Translation from Pascal===
<lang lisp>(defun pascal (r)
(dotimes (i r)
(let ((c 1))
(dotimes (k (+ i 1))
(princ (format "%d " c))
(setq c (/ (* c (- i k))
(+ k 1))))
(terpri))))
</lang>
{{Out}}
From the REPL:
<pre>
ELISP> (princ (pascal 6))
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
</pre>
===Returning a string===
Same as the translation from Pascal, but now returning a string.
<lang lisp>(defun pascal (r)
(let ((out ""))
(dotimes (i r)
(let ((c 1))
(dotimes (k (+ i 1))
(setq out (concat out (format "%d " c)))
(setq c (/ (* c (- i k))
(+ k 1))))
(setq out (concat out "\n"))))
out))
</lang>
{{Out}}
Now, since this one returns a string, it is possible to insert the result in the current buffer:
<pre>
(insert (pascal 6))
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
</pre>
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