## December 30, 2008

at
Tuesday, December 30, 2008
Labels:
Computer Science,
Lisp,
Project Euler
Posted by
Billy

If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.

If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?

NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and forty-two) contains 23 letters and 115 (one hundred and fifteen) contains 20 letters. The use of "and" when writing out numbers is in compliance with British usage.

(defun remove-hyphens (str)

"Removes any hyphens from str"

(remove #\- str))

(defun remove-spaces (str)

"Removes any spaces from str"

(remove #\Space str))

(defun euler-17 ()

(+ (loop for i from 1 to 1000 sum

(length (remove-hyphens (remove-spaces

(format nil "~R" i)))))

;; SBCL does not include the word 'and', so add

;; those letters also

(* 3 99 9)))

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